It isn't a silly question, Angela. To remove the reel and bedknife (you normally have them sharpened together) you will have to remove the chain that drives the reel. It is inside the cover on the left side of the mower, if you are facing forward. The engine does not affect doing this, so it does not really matter whether it is on the mower at the time or not. You remove the chain by finding its joining link and removing it. It is the same as a bicycle chain.
Our resident expert on the frames, clutches and cutting systems of reel-type mowers is Deejay. He can help you with specifics of how to go about the sharpening, adjusting etc. Please do not sharpen the blade and then reinstall it without getting advice from Deejay, your local reel sharpening technician, or both - otherwise you may undo all the good work done by the sharpening.
