1995 VW Jetta Cap and Rotor replacement

My son and I were working on his VW trying to replace the cap and rotor. We had a couple of problems. Despite numerous assurances that the rotor would just pull off we could not get it to budge. Second, deciding to leave it and just deal with the cap, I broke one of the retaining clips. So, should the rotor just pull off and. more importantly, have I done myself in breaking the cap retaining clip?