 had an entry with User and Host column values of 'bob' and
'%.loc.gov', you would write the statement like this:

SET PASSWORD FOR 'bob'@'%.loc.gov' = PASSWORD('newpass');

If you want to delete a password for a user, you would do:

SET PASSWORD FOR 'bob'@localhost = PASSWORD("");

URL: https://mariadb.com/kb/en/set-password/https://mariadb.com/kb/en/set-password/