Several features of grosh depends on the user permitting the app to access the location. For instance, the app needs to know where you are in order to tag a shopping trip with the store name. Also to provide sorting of the shopping list according to the store layout. Additionally, if you’re in a shop, the meaning of left swipe on the shopping list changes meaning from Delete to Hide (to declutter the shopping list).
You should be able to use Grosh without granting this permission, but you will see a warning now and then about failure to access your location. And of course none of the features based on location will work.
If you would like to revoke location permissions, this depends on the iOS/Android version you’re using. With the latest iOS, go to Settings - Grosh - Location to change your location settings. On the latest Android version, goto Settings - Apps - App Permissions - Location - Grosh.