You could uncap the honey in that 3rd super and put back on the hive for the
bees to draw down. To help encourage that, put inner cover on top of brood
box, then empty box, then super with uncapped honey, then top cover (add a
second inner cover, if you have one).

When uncapping that honey, work quickly with an unheated knofe or scratcher
or you'll get other bees started in a robbing attempt. Also, make sure there
are no cracks or holes they can use to enter the hive above the inner cover
and rob the honey away from this hive. Either tape up, or stuff full of
grass if you find any (or the bees find them for you -- one hive I had
drawing down had this problem earlier).

Or, if you are going to treat with fumidil for nosema, take that honey home
with you and feed syrup now - two gallons per hive for treatment (according
to my label). Remember that if you leave the honey super on and treat with
apistan (or presumably any of the other chemicals), you not only can't use
any of the honey, but can't use that super for honey production in the
future (possibly you could melt all the wax and boil/burn everything out and
maybe get all the residue out so that you could get fresh foundation drawn
out for next year).

-Karen