You will need to move the CMOS reset jumper found at the bottom of your motherboard.
Refer to the Hardware Maintenance Manual (HMM) for your particular model. The HMM can be found on the Lenovo support website.
Follow these steps:
1. Disconnect the power cable from the back of your system
2. Press and hold the power button until you hear the capacitors drain
3. Open the access panel and move the CMOS jumper from pins 1 + 2 to pins 2 + 3
4. Plug in the power cable and boot your system
5. Turn off your system when you hear a beep
6. Move the CMOS jumper from pins 2 + 3 back to 1 + 2 and boot your system as normal
This will clear all of your settings in the CMOS, including the power-on, user, and administrator passwords. This process will not clear any hard drive or solid state drive passwords that might be set or affect your operating system passwords.