It sounds like your Mac is keeping the cached files, despite the app deletion. Clearing the cache files should work.Here are the steps, just in case:
1. Quit Slingplayer Desktop. Don't just close the window, make sure the app is no longer running in the Dock
2. Go to the Finder (desktop), and select Go > Go to folder
3. Enter: ~/Library/Application Support/ and click Go
4. Move the following folders to the trash: com.slingmedia.SlingPlayer-Desktop.cefCache, SlingPlayerDesktop, and SlingPlayer Desktop. The last folder might not be present, which is OK.
I hope this helps!
Sling Media Technical Support