What is the best way to reset my Lenovo Computer?

Depends on the Lenovo model. My G555 had a special button for resetting. Does yours? Or do you have a different one. With your secret model, it is now up to you to search for answer. Contact Lenovo or use Google.

Define 'reset.'

Do you want to reinstall Windows, reset your password, delete all your data, stop a runaway process, flush a stalled print job, or? If you want to brute-force the power Off, press and hold the Power button for 5 seconds. If you want to do it right, go through a normal Shutdown procedure -- there are no shortcuts.

I want to delete all my data.