You can remove the roof but it's an arse and it looks a bit odd. You can even get a soft-top conversion kit for it and fit an Elise soft top if you want.
ETA: Assuming you mean the S2. I dunno about the S1.
Edited by kambites on Wednesday 10th September 15:21
While S1 roof is technically removable, you've got to remove the rear clam to do it. Also the engine cover hinges from the roof so you can't convert it to a soft-top.