I recently started having issues with my Yubikey / Security Key that I use for Gitea, and was unable to login.
This explains how to fix it.
Connect to the database. I only have a single user, and so I use the sqlite3 database backend.
$ sqlite3 gitea.db
sqlite> select id from user where name="wkumari";
sqlite> delete from u2f_registration where user_id =1;
This still didn't work -- and then I noticed that the url ended in 'webauthn', so I also did:
$ sqlite3 gitea.db
sqlite> select * from webauthn_credential;
sqlite> delete delete from webauthn_credential where id=2;
Done!