You sure can!...just make sure that you drink sufficient water with the shakes, as well as throughout the day. Fiber...along with sufficient water...helps to bulk up the stool and enable them to pass more easily...which is helpful when hemmorhoids are present. If you don't drink enough water, though, you can easily become constipated...which is NOT helpful for hemmorhoids!
If your hemmorhoids are currently inflamed &/or bleeding...you may want to wait until they have settled down before beginning the cleanse.