Reset Mac user password via SSH
This might still work?  If you log in with SSH.
FSCK the drive for a sanity check.
/sbin/fsck -fy

Mount the drive so it is writeable.
/sbin/mount -uw /

Deleting this placeholder file that tells macOS that a user has already been setup.
rm /var/db/.AppleSetupDone

reboot. Make a new user, reset the password of the old account.  Also, reset the login keychain in the old account.