Removing the radiator will definitely not solve the issue. It will just hide the symptom temporarily until it arises in a worse state a little later down the line in the next radiator from the end of the system.
If you have sludge in your system it will definitely get worse and then be harder to clean out and eventually affecting the heat exchanger of the boiler itself. The radiator in question is probably the last radiator on the system and therefore has the least amount of velocity within the system. If sludge was the only issue here, then simply removing the radiator, washing out in your back gardem with a power hose, etc. would remove the sludge and would temporarily resolve the issue in that radiator. But at least you would know that the only issue with your system is sludge build up and a powerflush will definitely remedy this.
More to the point, at a guess, I am wondering do you have a drop down system? To know, does your pipes leading to your downstairs radiators come out of the wall or are they coming up from the floor? If from the wall, you have a drop down system. If so, let me know and I will explain the issues with this type of system.
Also check the head of the circulating pump in the gas boiler. Is it a 15/50 or is it a 15/60? It will be written on the pump head itself.
My guess is you have a drop down system and a 15/50 circulating pump.
To resolve, you need to powerflush the system, put a decent inhibitor in, such as Fernox F1, and replace the pump head with a 15/60.