Run DCS world, then press CTRL + ALT + DEL, open task manager and go to the list of running tasks. Find the DCS .exe and it'll say DCS_World.exe*32 if its running in 32bit and your running a 64bit OS
Dont have access to a pc just now so i may not be using the correct naming.
Edit: back on a PC. It's the Processes tab in the task manager you want and you're looking for DCS.exe