Yes, you can. It might require changing the size of the door opening, which is not a trivial job. It has to be framed in properly. If the existing door is the same size as the prehung door it may Just Work. This is more likely for interior than exterior doors. Measure and measure again, and do not forget to measure how thick the door is, as well as how tall and how wide.

I'm nearly to the point of replacing my interior doors. The width (30'') isn't as common, but it was in stock at HD. The thickness is the same, and my doors are a bit shorter, but I'm going from carpet to laminate, so I need slightly taller doors, and I believe there's room to trim the door slightly if need be. The biggest difference is the door jamb. The prehung door jambs are about 1'' wider than my current door jambs. My contractor said he can pretty easily trim the door jambs, though.