You can easily uninstall the app via the Shopify app overview.
To do this, simply navigate to Settings > Apps and sales channels.
Click on the three dots next to geolizr and select Uninstall:
More details you can find here: https://docs.shopify.com/support/configuration/apps/how-do-i-uninstall-an-app.
The subscription will be cancelled automatically as soon as you have uninstalled the app.