if i recall correctly, in Man of Steel, superman's superpowers are not by definition concidered superpowers. to humans, obviously, they are, but - superman's cells are conciderably stronger than 'earthling' powers.
i believe it was said to derive from his prolonged exposure and adaptation to certain elements of Earth's atmosphere as well as Earth's Sun. Supes is depicted as being more powerful than Zod and other Kryptonians due to his lifetime of exposure to Earth's yellow sun, which allowed him to absorb and metabolize its radiation in greater amounts and with more efficiency. This gave him an advantage and victory over them despite their superior fighting skills and quickly adapting to their newfound abilities.
So, taking this into account, you could state 'superman' by definition does not have superpowers. He is simply much stronger than humans - or, lets say he does not need anything special for his superpowers. As for example some elixer, a certain thing in his blood, or a spell like thor (his powers were taken from him, so he's not by definition strong by gene, if you'd like to look at it that way).
So really, you can't take away supes powers. You could concider having him away from the sun would slightly weaken him over time.
either way, the idea of a superpowerless superman i simply can't enjoy. Superman is superman because he's so super strong. Without it he's, what? an useless uninteresting character. It would actually weaken the character to be able to lose his superpowers. That would turn supes in somebody dependant of 'something'. This superman is an Alien that is superbly strong by birth in comparison to humans.
Being allergic to kryptonian radiation would be enough imho. weakening him. thats more than enough.