Syntax:
REVOKE
    priv_type [(column_list)]
      [, priv_type [(column_list)]] ...
    ON [object_type]
        {
            *
          | *.*
          | db_name.*
          | db_name.tbl_name
          | tbl_name
          | db_name.routine_name

        }
    FROM user [, user] ...

REVOKE ALL PRIVILEGES, GRANT OPTION FROM user [, user] ...

The REVOKE statement enables system administrators to revoke privileges
from MySQL accounts. 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
[HELP GRANT].

To use the first REVOKE syntax, you must have the GRANT OPTION
privilege, and you must have the privileges that you are revoking.

For details on the levels at which privileges exist, the allowable
priv_type values, and the syntax for specifying users and passwords,
see [HELP GRANT]

URL: http://dev.mysql.com/doc/refman/5.0/en/revoke.html

