You may force the Draggable to immediately stop interactively dragging by calling endDrag() and passing it the original mouse or touch event that initiated the stop - this is necessary because Draggable must inspect that event for various information like pageX, pageY, target, etc. You cannot call endDrag() without passing that original event.
endDrag() is different than disable() in that disable() completely shuts down the Draggable instance so that the user cannot initiate dragging anymore whereas endDrag() simply stops a drag-in-progress, acting like the user released their mouse/touch.