DROP USER user [, user] ...

The DROP USER statement removes one or more MySQL accounts. To use it, you must have the DELETE privilege for the mysql database. Each account is named using the same format as for the GRANT statement; for example, 'jeffrey'@'localhost'. If you specify only the username part of the account name, a hostname part of '%' is used. For additional information about specifying account names, see Section 12.5.1.2, “GRANT Syntax”.

DROP USER was added in MySQL 4.1.1. In MySQL 4.1, it serves only to remove account rows from the user table for accounts that have no privileges. To remove a MySQL account completely (including all of its privileges), you should use the following procedure, performing the steps in the order shown:

In MySQL 5.0.2 and up, DROP USER removes the account row in the user table and also revokes the privileges held by the account. It is not necessary to use DROP USER in conjunction with REVOKE.

Before MySQL 4.1.1, DROP USER is not available. You should first revoke the account privileges using SHOW GRANTS and REVOKE as just described. Then delete the user table row and flush the grant tables as shown here:

mysql> DELETE FROM mysql.user
    -> WHERE User='user_name' and Host='host_name';
mysql> FLUSH PRIVILEGES;