How to check (and close) processes in a loop?

In my keyword tests, I need to check on some active processing before starting execution.

However, if these processes are active, I need to close them. 

I do not know how many instances of these processes are active, if they are active.

I used a While loop to close processes (which works), something (while process exists, close process), however when the last process is closed I get an error in the While loop because the process is not found (which is true), and TC gives me an error.

What is the best approach to tackle this situation?