it will be frozen on, or soon after, declaration. Any monies in the account will not be accessable until the OR is satisfied who the monies belong to. The bankrupt or the non bankrupt. The OR will claim any monies deemed to belong to the bankrupt unless it can be demonstrated that those monies are required to meet essential expenditure.
Once this is all resolved the account will most probably be closed, this is the bank's decision not the OR's. It's messy
Either remove the intended bankrupts name from the account before bankruptcy or remove all funds from it, again before bankruptcy, and accept that the account will be closed.