DIY Doctor UK DIY Forums

Hi, i have been trying to drain a radiator with a thermo tvr valve however it wont shut off, i have been told to use a 5p inside the valve because they dont close when turned off, however it still not closing, can you advise on how to remove and drain the radiator without having to drain the whole system, I know when you remove the top of the valve theres a small pressure pin, i have tried to close 2 in the same room and both wont close is there any tool that can be used ?
thanks