There is no proper way to forcibly kill a thread.
There are several ways to do it, but none of them are proper.
Forcibly killing a thread is what you should do only if you need to terminate the program, or unload the appdomain containing the thread, and don′t care about any data structures left dangling in a corrupted/bad/locked state, because they will be gone in a short while as well.
There′s plenty of advice on the internet about how bad/evil Thread.Abort is, so don′t do it.
Instead, write proper cooperative threading. The thread(s) should themselves check a flag (event, volatile bool field, etc.) and then voluntairly exit when nicely asked to do so.
That is the proper way.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…