Are you meaning turning it into two cages? Best way to do it is to make a melamine 5-sided box (sides and bottom) and rest it just below the top door. Use screws and washers to hold it in place (many!) and a couple wooden supports may be necessary, if it fell it would be fatal to the chin below.
I've had this cage before. It wasn't bad, but most Superpet cages have the same issues.