Hot water radiator removal

Since you probably do not have valves at both ends of the radiator, (and even if you did, they are not designed for complete watertightness), you will have to drain the system, at least to a level below that radiator. if you wish to refill the system to get heat, then you will have to cap off the two pipes. If the valve is that tight, you should replace it while the radiator is disconnected. : : Im doing some re-tiling in my bathroom and need to take out my radiator to tile behind it. Can I just shut off the valve on the radiator and disconnect it from the main system or do I need to drain the entire system? There are feed pipes to and from the main hot and cold pipes downstairs so it looks like it shouldnt interfere with the rest of the radiators if I just shut this one off… Do I need to cap either end? : And finally, my valve is really stuck, probably from being painted several times. Any suggestions on how to open it up? Thanks!