How do I clear out a large area of spiders from a monster spawner?

I have made a terrible mistake on cubecraft’s SkyBlock.
I have made a spider farm, it is very secure (so no spiders can get out) but i put all of the spawners in one area.
Now, whenever i enter the room (with all the spawners in it) I get swarmed by all the spiders and see the dreaded "you died" screen.
I need to get into the room, destroy the spawners then kill all of the spiders.
I have tried many ways to accomplish this task such as using water, trying my luck with a sword, building over, under and behind the farm, but none of them have worked so far.
I need a solution to this problem.
For informational purposes;
I am on the fourth island (Jungle),
I have a bane of arthopods sword and a fire aspect sword
and I’m on a solo profile.