Do you mean RDC for Mac from Microsoft?
If the above is what you mean you may find it in your downloads folder (assuming you used Safari) or your Applications folder (assuming you moved it there after you downloaded it?). If you don't see it in either of those locations try searching for it using Spotlight (top right hand corner of your screen - looks like a magnifying glass). If you key in RDC it should come back as Remote Desktop Connection. Select "Show All in Finder" and hopefully you'll track it down from there. It does not actually install anything anywhere else as everything it needs it carries within itself so simply taking it to the Trash and emptying it will remove it. In your home folder (the little house icon in the Go Menu) Document's folder you may see a folder named RDC Connections which you can also safely delete.
This forum is dedicated to Apple's Apple Remote Desktop which, although similar, is not the same thing as Microsoft's RDC for Mac.