To uninstall Grid Calculator Pro Edition just follow along in this guide.
Applications > Adobe InDesign CSX or CC X > Plug-Ins > Grid Calculator Pro Edition > Uninstaller. Run the uninstaller and if needed, deactivate license.
On some operating systems you might need to manually delete the plug-in folder of Grid Calculator Pro Edition to remove the plug-in, if the uninstaller does not run properly.
Uninstallation is easiest done via the Control Panel, just double- or right-click and uninstall. If needed, deactivate license.