It would be like trying to remove a modest mountain. It could be done, with modern strip mining equipment, but it wouldn’t be as dramatic as blowing up those Buddhas in Afghanistan
Nope it's easy! Gravity is an awfully good assist, just roll them down from the top. The 'outside skin' has completely gone from 2 of the 3 pyramids, and almost completely gone from the 3rd, where the outer casing still remains at the top. Reason - "we wanted that nice stone for building other stuff." And have you seen the TV program about the 4th pyramid, now completely gone? Reason: "we wanted the limestone to make cement." All this in ancient times without strip mining equipment.