Question about business lease?

I live in New York my husband and I rented a building for 6yrs, well the building went into for closure. The bank let us keep our Business open and now someone bought the building and the bank wants us to sign off the lease so the other people who bought the building can open there own business, We are opening up another location just in case we half to go but we don't wanna leave just yet because we wanna see how the other location works out. My question is do we half to sign off the lease we still have 4 yrs left?