I fully agree with Paul on his recommendation to do a clean install via the HP Cloud Recovery approach. However, there are some settings that may have been set within BIOS that were locked in place and password protected. The best approach on this is to go into BIOS and set BIOS to "factory settings" and save on the way out of BIOS. This should get you back to the BIOS settings HP sent the PC out from the factory with.
However, if there are settings in BIOS that were password protected, we cannot help you with those. It is a forum rule that such advice is not provided here. Rather, you'd need to work directly with HP on that if you have such a situation or read your service manual for related information.