I've downloaded the installation package and it appears that it installs just like any regular application. To remove it, go to Control Panel and then click on Uninstall a program, under the Programs category.
If you have issues with this installation, then use Revo Uninstaller. Even if it can't uninstall the application normally, it will force it to uninstall by wiping out all traces of its presence from the system.
Reboot your PC, start Revo again and check the presence of the Sims 4 Tray Importer.