Hmmm
That may be difficult for a couple of reasons.
The drum may have absorbed the oil and the other issue is that the drum
has a lubricant which may have been affected and when you clean the
drum you will remove the lubricant (dry powder).
I suggest the use of isopropyl alcohol (rubbing alcohol) as pure as you
can find (preferably better than 91%). Apply it with care and as
sparingly as possible with cotton wool buds or similar. Try not to
apply it to any unaffected areas.
Hopefully it will work and you will not suffer from a drum that binds
afterwards because of the missing lubricant.
Good luck