$('.remove-selected').on('click', function(){
    deleteObjects();
})
function deleteObjects(){
  var activeObject = canvas.getActiveObject();
   if (activeObject['_objects'] === undefined) {
       canvas.remove(activeObject);
   }else{
     for(var i=0; Object.keys(activeObject['_objects']).length > i;i++){
        canvas.discardActiveObject();
        canvas.remove(activeObject['_objects'][i]);
      }
  }
}