1.
to be able to be removed :
Does this hood come off?
That mark won't come off.
2.
( informal ) to take place; to happen :
Did the trip to Rome ever come off?
3.
( informal ) ( of a plan, etc. ) to be successful; to have the intended effect or result :
They had wanted it to be a surprise but the plan didn't come off.
4.
come well, badly, etc. ( informal ) to be successful / not successful in a fight, contest, etc. :
I thought they came off very well in the debate.