The first easy way is to remove the CMOS battery from the motherboard. Here we will show you the procedure collected from wikihow.com:
1. Power off the computer. Either use the Start menu to shut down the computer, or press and hold the computer's power button until the computer shuts down. If you are using a desktop computer, you can usually turn off the CPU completely by pressing the switch on the back of the CPU case.
2. Unplug your computer. This includes power cords for desktop computers and charging cords for laptops.
3. If necessary, remove the computer battery. If you are using a laptop computer (or desktop with a battery backup), remove the battery before continuing.
4. Discharge any static electricity before continuing. Before you begin disassembling the computer, touch an unpainted metal surface to eliminate static electricity. Touching the motherboard or other internal computer components without proper grounding may permanently damage the computer.
5. Open the chassis. You need to be able to reach the computer's motherboard. Be very careful when working inside your computer because static discharge can easily damage sensitive components.
For many laptops, you can access the CMOS battery through a removable panel on the bottom of the laptop. If there is no panel, you will likely need to disassemble the laptop to access the battery.
6. Remove the CMOS battery. The battery is usually located near the PCI slot, but may be in a different location depending on the motherboard manufacturer. It may be hidden by expansion cards and cables. The battery is usually a standard 3V, round, flat watch battery (CR2032).
The CMOS battery is not always removable. If the battery cannot be removed, do not force it out, but try resetting your motherboard's jumper.
7. Press the power button. Press and hold the computer's power button for about 10-15 seconds to discharge the remaining power stored in the capacitor. By discharging the capacitor, the CMOS memory will be reset, thus resetting the BIOS.
8. Reinsert the CMOS battery. Carefully reinstall the CMOS battery into the housing. Make sure the battery is oriented correctly. The smaller side should be facing down.
9. Reassemble the computer. Handle with care and remember to ground the computer periodically.
10. Reconnect the computer's power supply. If you unplugged the computer from the wall and/or removed the battery, plug it back in and/or replace the battery.
11. Turn the computer back on. Depending on your computer, you may need to access the BIOS and reconfigure certain options, including the default boot options or the date and time.
The second method: reset the jumper (not recommended, easy to hurt the motherboard, this kind of man-made problems do not provide free warranty service)
1. Power off the computer. Either use the Start menu to shut down the computer, or press and hold the computer's power button until the computer shuts down. If you are using a desktop computer, you can usually turn off the CPU completely by pressing the switch on the back of the CPU case.
2. Unplug the computer. This includes the power cord for desktop computers and the charging cord for laptops.
3. Remove the computer battery, if necessary. If you are using a laptop computer (or a desktop computer with a backup battery), remove the battery before proceeding.
4. Discharge any static electricity before continuing. Before you begin disassembling the computer, touch an unpainted metal surface to eliminate static electricity. Touching the motherboard or other internal computer components without proper grounding may permanently damage the computer.
5. Open the chassis. You need to be able to reach the computer's motherboard. Be very careful when working inside the computer because static discharge can easily damage sensitive components.
6. Locate the CMOS jumper. Locate the three-pin jumper on the motherboard that controls the BIOS. It is usually located near the CMOS battery. The jumper will cover two of the three pins.
The jumper may be labeled "CLEAR", "CLR", "CLEAR CMOS", "PSSWRD", or various other labels. Refer to your motherboard documentation to find the correct jumper.
7. Move the jumper to the other two pins. For example, if the jumper is covering the first and second pins, move it so that it is covering the second and third pins. Be sure to pull the jumper straight up to remove it so that you don't bend the pins.
8. Press your power button. Press and hold the power button on your computer for about 10-15 seconds to discharge any remaining power stored in the capacitors. This will make the BIOS reset.
9. Place the jumper back to the default position. Place the jumper back on its original pin. This will allow you to access the BIOS when booting the computer.
10. Reassemble the computer. Handle with care and remember to ground the computer periodically.
11. Reconnect power to the computer. If you unplugged the computer from the wall and/or removed the battery, plug it back in and/or replace the battery.
12. Turn the computer back on. Depending on the computer, you may need to access the BIOS and reconfigure certain options, including the default boot options or the date and time.
Third method: Reset from inside BIOS
1. Restart your computer. Open Start 
, click the power icon
, and click Restart.
If the computer is locked, click the lock screen, then click the power icon in the lower right corner of the screen, then click Restart.
If the computer has shut down, press the computer's On switch.
2. Wait for your computer's first startup screen to appear. After the startup screen appears, you have a very limited window in which you can press the Setup key.
It's best to start pressing the Setup key as soon as the computer starts to reboot.
If you see the words "Press [key] to enter settings" or something similar flash at the bottom of the screen and then disappear, you will need to reboot and try again.
3. Repeatedly tap Del or F2 to enter settings. The key you are prompted to press may also be different; if so, use that key.
If Del or F2 doesn't work, try F8 F10 Esc or Tab ↹.
You will usually use the "F" keys to access the BIOS. these keys are located at the top of the keyboard, although you may need to locate and hold down the Fn key while pressing the correct "F" key.You can check your computer's model manual or online support page to confirm your computer's BIOS keys.
4. Wait for the BIOS to load. After successfully pressing the Setup key, the BIOS will load. This will only take a few moments. After loading is complete, you will be in the BIOS setup menu.
If you are unable to access the BIOS because the password is locked or the BIOS is corrupted, use one of the alternative methods in this document.
5. Find the "Setup Defaults" option. The location and wording of this option varies for every different BIOS, but it will typically be called "Reset to Default", "Factory Default", "Setup Defaults", or something similar. It may be located in one of the tabs or it may be an option listed near the navigation buttons.
If your BIOS does not have this option, use one of the methods below in this section.
6. Select the "Load Setup Defaults" option and press ↵ Enter. Use the arrow keys to select it; pressing ↵ Enter will usually begin resetting your BIOS immediately.
Similarly, the wording of the selected options may be different for each BIOS.
7. Save the changes and confirm the selection if necessary. This is usually combined with the process of exiting the BIOS. The computer will reboot automatically.After the BIOS reset, if you need to change the BIOS settings, you may need to reboot the computer again and enter the BIOS to make the changes.
