The crankcase vent has a hose that goes from the top of the engine to the front of the air box.  The vapors are burned by flowing with the air stream through the carb.  Any oil or water that condenses out of the vent goes into a small chamber at the front of the air box.  There is a drain hose that is supposed to be capped, and that hose is under the engine at the back of the engine.  You are supposed to remove that cap and drain the "catch" system periodically .....like when you change oil.

You don't need to take anything off.

There should be a black cap at the end of the hose - you just take that off and let the goo drip out.  If you don't have a cap - you should plug or cap that hose with something so that dirt cannot be sucked up the pipe when the engine is running.

If you want to wipe the inside of the air box down that is fine - but most the time it is not necessary.  The air flow toward the engine should have kept any oil from getting on the backside of the air cleaner.

Ya, I went ahead and did that and a bit of oil came out so hopefully that will stop the drip.

But now my belt is a little squeeky from the oil getting on it.
It does not look dry or cracked or anything, is there a product I can use to fix that noise?