Not doing the execute of the return query from a cursor

[efmdba]

CREATE OR REPLACE function  user_drop (p_user   in   text)
returns setof record  AS $BODY$ 
DECLARE
   sql_new_statement text;
    cur_user_roles CURSOR(p_user  text)
      for    select 'revoke '||c.rolname||' from '||a.rolname||';'
              from pg_catalog.pg_roles a
              inner join pg_auth_members b on a.oid=b.member
              inner join pg_roles c on b.roleid=c.oid 
              where a.rolname = p_user;
    BEGIN
       open  cur_user_roles(p_user);
       loop
       FETCH cur_user_roles into  sql_new_statement;
        raise notice 'Value: %', sql_new_statement;
        return query execute ''''||sql_new_statement||'''';
        raise notice 'Value: %', return_query;
       EXIT WHEN NOT FOUND;
       raise notice 'Value: %', sql_new_statement;
         commit;
    END LOOP;
   CLOSE cur_user_roles;
return;
exception
   when others then
    null;
END;
$BODY$ LANGUAGE plpgsql;

The return query execute ''''||sql_new_s tatement||''''; is not executing the sql showing in sql_new_stateme nt.