They don't have to clean up the whole span, just the shipping channel for now.
Cut a piece off, hoist it out with a barge with a crane. Next piece.
Cranes with grappling hooks can dump the steel onto barges where it can be cut with torches into smaller easier to manipulate pieces. Some cutting will probably be done with workers in lift buckets, if any divers have to do cutting, I pray for their safety. This shouldn’t take that much time, I’m thinking a couple months, and I agree, concentrate on the channels and open up the harbor.