The plastic shell is not removable (except for repairs perhaps) and is held solidly in place by two tiny screws on the base of the handset, positioned either side of the USB 2.0 port. (mobilegeeks.com)
On the Torch, the keyboard sits recessed in the base of the handset, so there is a ridge that runs around the keyboard which forms part of the handset construction. (pocket-lint.com)