DROP ROLE [IF EXISTS] role [, role ] ...
        DROP ROLE removes one or more
        roles (named collections of privileges). To use this statement,
        you must have the global DROP
        ROLE or CREATE USER
        privilege. When the read_only
        system variable is enabled, DROP
        ROLE additionally requires the
        CONNECTION_ADMIN privilege (or
        the deprecated SUPER privilege).
      
        Users who have the CREATE USER
        privilege can use this statement to drop accounts that are
        locked or unlocked. Users who have the DROP
        ROLE privilege can use this statement only to drop
        accounts that are locked (unlocked accounts are presumably user
        accounts used to log in to the server and not just as roles).
      
        Roles named in the
        mandatory_roles system variable
        value cannot be dropped.
      
        DROP ROLE either succeeds for all
        named roles or rolls back and has no effect if any error occurs.
        By default, an error occurs if you try to drop a role that does
        not exist. If the IF EXISTS clause is given,
        the statement produces a warning for each named role that does
        not exist, rather than an error.
      
        The statement is written to the binary log if it succeeds, but
        not if it fails; in that case, rollback occurs and no changes
        are made. A statement written to the binary log includes all
        named roles. If the IF EXISTS clause is
        given, this includes even roles that do not exist and were not
        dropped.
      
Each role name uses the format described in Section 8.2.5, “Specifying Role Names”. For example:
DROP ROLE 'admin', 'developer';
DROP ROLE 'webapp'@'localhost';
        The host name part of the role name, if omitted, defaults to
        '%'.
      
A dropped role is automatically revoked from any user account (or role) to which the role was granted. Within any current session for such an account, its adjusted privileges apply beginning with the next statement executed.
For role usage examples, see Section 8.2.10, “Using Roles”.