lop (something) off
To cut something off or away, especially quickly, indelicately, or without finesse. I had been growing my hair out since I was in junior high school, and then one day I decided to lop it all off. The knight lopped off his arm for his insubordination. Will you go out back and lop those branches off the tree? They're obstructing our view of the sea.
lop something off (of) something
and lop something offto chop or cut something off something. (Of is usually retained before pronouns.) Lop that long branch off the tree before you put the saw away, will you? Please lop off that branch.
lop off
v. To cut something off; chop off: The barber lopped my ponytail off. The gardener lopped off the dead branches.