Remote Desktop Manager doesn't install anything in the Windows System directory. The only registry settings created are for the auto-run functionality and the installation path. As a result, Remote Desktop Manager can be uninstalled easily.
You can run the uninstaller if it was installed with the default setup file or delete the installation folder directly if it was installed from the binaries.
The application configuration files are saved in "%LocalAppData%\Devolutions\RemoteDesktopManager" or "%AppData%\Devolutions\RemoteDesktopManager" by default. It's possible that you may want to delete this folder for a complete uninstall.