Many thanks for sharing.
Does this only allow to create a new additional admin account, or does it replace the old one as well?
Here are also instructions in case the user got locked: https://jellyfin.org/docs/general/administration/troubleshooting.html#unlock-locked-user-account
The reset password feature is another alternative, when configured.
And finally I guess it would be possible to apply a new password directly to the database as well. We’d just need to find out how it is hashed or encrypted there.