If you have not medicated the hive at all, you can insert new top bars into the brood nest, which pushes the older combs farther back in the hive. The bees will draw comb on the new bar and raise brood in that. The old combs which are furthest back will get filled with honey. You can then crush and strain this honey and you will be rid of the old comb. You could also try to move the older comb, one top bar at a time, to the very back of the hive. It is doubtful that the bees would abandon the brood, and once it has all hatched, you can then take the comb out.