You can drop custom roles, but not default roles.
Drop a role by using an SQL statement
Use the DROP ROLE statement to drop a role that is no longer needed. To drop a role, you must have the system privilege DROP ANY ROLE and have been granted the WITH ADMIN OPTION privilege for the role to be dropped.
For information about how to view your privileges, see View user privileges. If you do not have the required privileges, contact the administrator to obtain the privileges. For information about how to grant privileges to a user, see Modify user privileges.
When you drop a role, the system revokes the role from all users and roles that have been granted the role and then drops the role from the database.
Notice
Dropping a role does not affect user sessions in which the role has already been enabled. However, after the role is dropped, if a new user session is established, the role cannot be enabled in the new user session.
The syntax is as follows:
obclient> DROP ROLE role_name;
Here is an example:
obclient> DROP ROLE role1;
Query OK, 0 rows affected
For more information about the DROP ROLE statement, see DROP ROLE.