How to block IDM in the router?

Hello everybody,
I need some help from you guys. How to block IDM in the router? Here in our company we are using 6 computers and we are all internet connected and we are using D-Link DIR-652. I just noticed that the 6 pc units have IDM installed in it and it really affects the internet connection. I just want to get the normal speed for downloads for limitation and security purposes.
Thanks.
