I have a 4cmstomach ulcer and i have the lapban in do i need to remove the lapban for the ulcer to heal?

Not necessarily: Generally no unless the ulcer is do to an eroding band. If the ulcer is distal to the band, no. If the ulcer is above the band and due to freq reflux then remove the fluid from the band and allow to heal with medical therapy. If actively treating an ulcer, it may be advisable to remove the fluid to allow adequate therapy and not create problems.

Maybe: 4cm is a very large ulcer. If it is near the band, then at the very least you should probably have the band deflated and be placed on anti-acid medication. If it is not near the band, maybe meds alone will help. In any case, you should see the surgeon that placed the band for specific advice.