For resetting Lenovo Thinkpad power-on password, I think you can read the following article. It is helpful for you:
Reset Forgotten Power-on Password
If the Power-on password is forgotten and the Supervisor password is known, simply go into the ThinkPad BIOS setup utility and reset the Power-on password, otherwise try the following:
1.Power off the Lenovo ThinkPad computer
2.Remove the battery pack
3.Remove the backup battery
4.Please power on the computer and wait till the POST ends. If the password prompt does not appear then the Power-on password has been reset.
5.Reinstall the backup battery and the battery pack.
Note: Some ThinkPad systems have the ability to reset the Power-on passwords in the ThinkPad BIOS setup utility if a Supervisor password has been set.