Syntax
------ 
DROP USER [IF EXISTS] user_name [, user_name] ...
 
Description
----------- 
The DROP USER statement removes one or more MariaDB
accounts. It removes
privilege rows for the account from all grant tables. To use
this statement,
you must have the global CREATE USER privilege
or the DELETE privilege for the mysql database.
Each account is named using the same format as for the
CREATE USER
statement; for example, 'jeffrey'@'localhost'. If you
specify
only the user name part of the account name, a host name
part of '%' is
used. For additional information about specifying account
names, see
CREATE USER.
 
Note that, if you specify an account that is currently
connected, it will not
be deleted until the connection is closed. The connection
will not be
automatically closed.
 
If any of the specified user accounts do not exist, ERROR
1396 (HY000)
results. If an error occurs, DROP USER will still drop the
accounts that do
not result in an error. Only one error is produced for all
users which have not
been dropped:
 
ERROR 1396 (HY000): Operation DROP USER failed for
'u1'@'%','u2'@'%'
 
Failed CREATE or DROP operations, for both users and roles,
produce the
same error code.
 
IF EXISTS
 
The IF EXISTS clause was added in MariaDB 10.1.3
 
If the IF EXISTS clause is used, MariaDB will return a note
instead of an error if the user does not exist.
 
Examples
-------- 
DROP USER bob;
 
IF EXISTS:
 
DROP USER bob;
 
ERROR 1396 (HY000): Operation DROP USER failed for
'bob'@'%'
 
DROP USER IF EXISTS bob;
 
Query OK, 0 rows affected, 1 warning (0.00 sec)
 
SHOW WARNINGS;
 
+-------+------+---------------------------------------------+
| Level | Code | Message |
+-------+------+---------------------------------------------+
| Note | 1974 | Can't drop user 'bob'@'%'; it doesn't
exist |
+-------+------+---------------------------------------------+
 


URL: https://mariadb.com/kb/en/drop-user/