1  –  CASCADE

    Drops the specified role from the database and deletes all
    references to this role that exist in other roles and access
    control lists (ACLs).

2  –  IF_EXISTS

    Prevents SQL command language from displaying error messages if
    the referenced object does not exist in the database.

3  –  RESTRICT

    Drops the specified role. If there are any references to this
    role in another role or ACL, then the DROP ROLE statement fails.

    The RESTRICT clause is the default.

4  –  role-name

    An existing role-name in the database (such as one created
    with the CREATE ROLE statement). You cannot specify one of the
    predefined roles.