Here's an example of what can go wrong if you choose to remove a radiator (this is what happened to me today)
First problem was one of the lockshield valves had corroded and would not close properly, so I had to drain down the entire heating system - this took about 2 hours as there was no drain off point which meant I was running about with trays and buckets.
Got the radiator off, skimmed a couple of walls, refitted the radiator, and then started refilling the system using the filling loop (it was a combi boiler)
Got the system pressure up to 1 bar, and shut off the filling loop. This is when I found out that the valve on the filling loop decided to fail, and wouldn't shut off, meaning that the system pressure was rapidly rising until thankfully the blow-off valve opened once the pressure got to 3.5 bar.
Luckily I had a spare ballfix valve in the van, so was able to turn off the mains water, cut the cold supply pipe just before the filling loop, and fit the ballfix valve in line so that this could then be used to open/close the filling loop.
Got it sorted but it was a problem I could have well done without, it turned what should be been a nice easy day into a bleedin nightmare!