Git upload broken by new password policy

github has broken upload with the nuisance of enforcing “tokens” (i.e. longer passwords) to replace passwords.
And github is refusing to provide concise howto what to do to facilitate this superfluous transition. I use git command line commands which now report an error.
I know there are links to multiple pages explaining why, how, and what to do. I could spend a few hours of research to get this working again.
In particular, apparently, I “just” need to clear my credential cache in order to enter the new “password” - but nobody says how that works, which git command?