Old problem I know but I had same problem. Password to log into Admin account forgotten because used fingerprint reader for months. Options to change/remove password, password recovery disk and everything else requires password (which I could not remember) to proceed. I ended up doing the following.
Accessed admin account via fingerprint reader then created a new user account with admin priviledges. Logged out of first admin account, (had to do this twice for some reason.. maybe didn't log out properly) logged into second account. Selected Control Panel, User accounts, Manage another account, selected old account, choose remove password from old account, was given a warning/reminder but no password required. Logged out of new admin account, into old admin account with no password required. Added password to original account and all is now well.