Create a User

CREATE USER '${USERNAME}'@'${HOSTNAME}' IDENTIFED BY '${PASSWORD}';

You can use % as the host to act as a wildcard.

Alter a User

ALTER USER '${USERNAME}'@'${HOSTNAME}' IDENTIFIED BY '${PASSWORD}';

Root

Root is identified by root@localhost:

ALTER USER 'root'@'localhost' IDENTIFIED BY '${NEW_PASS}';

Delete a User

DROP USER '${USERNAME}'@'${HOSTNAME}';