Passwords are used for a reason and not able to be bypassed......easily.  If you absolutely have no idea what the password is you have two options.  Format the hard drive and reinstall Windows.  You will loose everything on the computer.  The second option is one that I've used once and was successful.  I purchased the following software and let it do its work.  I'm not sure what version I needed but I'm certain the Advanced option will do what you need.

https://www.isunshare.com/windows-password-genius.html#comparison