private ConfigOverlay applyDeleteHandler(CommandOperation op, ConfigOverlay overlay) {
   String name = op.getStr(CommandOperation.ROOT_OBJ);
   if (op.hasError()) return overlay;
   if (overlay.getReqHandlers().containsKey(name)) {
     return overlay.deleteHandler(name);
   } else {
     op.addError(MessageFormat.format("NO such requestHandler ''{0}'' ", name));
     return overlay;
   }
 }