Uninstalling on Windows
First, if it is currently running and visible on the taskbar, 'Stop & Quit' FolderSync. Then use File Explorer to open the folder C:\Program Files\FolderSync 
Within that folder you will find a program named FolderSync_Uninst.exe  - simply double click that program to run the FolderSync uninstaller.

Uninstalling on Mac OS X
Uninstall FolderSync on Mac just as you would any other application. Simply use Finder to drag and drop the FolderSync app from /Applications to the trash.