Designing Kitchens and Bathrooms - Drain in bathtub

My husband installed a new bathtub but used the wrong "cement" to glue in the metal drain in the tub. The metal drain is now corroding and we don't know how to get it out safely so it can be replaced). Any suggestions? Thanks

What type of "cement" did he use under the drain lip?
Only use plumber's putty under the lip of a drain for this very reason. (Wrap a pencil-sized roll of plumber's putty around under the drain lip, tighten the drain down, and clean off the excess.)
Depending upon the type of "cement" used, he might be able to dissolve it with an adhesive dissolver, such as Goo-Gone (available at hardware and grocery stores). Or he might try acetone (nail polish remover).
To protect the tub, use duct tape or masking tape around the drain, and soak the drain lip with a dissolver around the outer edge of the drain.
Try to loosen the drain with a drain wrench:
http://www.generich.com/customer/prodpics/web6169.jpg
Also, try to cut the cement loose with a thin knife blade under the lip.
Good luck! Mike