Revoking a Role from Users
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Use REVOKE to remove a role that you assigned to users.
The following statement revokes the DOITALL role from RENEE.
REVOKE DOITALL FROM RENEE;
RENEE no longer has any of the access privileges that she acquired as a result of membership in the DOITALL role. However, if any others users have granted the same privileges to her, she still has them.