MySQL 5.6 Release Notes
DROP USER user [, user] ...
The DROP USER statement removes
one or more MySQL accounts and their privileges. It removes
privilege rows for the account from all grant tables. An error
occurs for accounts that do not exist.
To use DROP USER, you must have
the global CREATE USER privilege,
or the DELETE privilege for the
mysql system database. When the
read_only system variable is
enabled, DROP USER additionally
requires the SUPER privilege.
Each account name uses the format described in Section 6.2.4, “Specifying Account Names”. For example:
DROP USER 'jeffrey'@'localhost';
The host name part of the account name, if omitted, defaults to
'%'.
Important
DROP USER does not
automatically close any open user sessions. Rather, in the
event that a user with an open session is dropped, the
statement does not take effect until that user's session
is closed. Once the session is closed, the user is dropped,
and that user's next attempt to log in fails.
This is by design.
DROP USER does not automatically
drop or invalidate databases or objects within them that the old
user created. This includes stored programs or views for which
the DEFINER attribute names the dropped user.
Attempts to access such objects may produce an error if they
execute in definer security context. (For information about
security context, see
Section 20.6, “Stored Object Access Control”.)