a dremel is a type of small preecise power tool, google it to see a pic. using a dremel or some other cutting device like cutting shears is best and really probably the only option if it is large. breaking it off by hand would be dangerous as you could break too close to the tissue and if its large and thick it may be really tough to do.
see the red line in this pic, thats where you would want to cut the hammer at.
[attachment=0]hammerfrag.jpg[/attachment]