Fresh install of an app

Hi, I have a local post office app that became buggy, constantly nagging me about unread messages (that don't exist thus I can't read them thus the unread message counter and the notifications never go away).

I would like to reinstall the app, tried to delete the data from the iCloud backups, I also tried to offload data and delete the app and then reinstall it, but the app got installed from iCloud even though I had deleted that data already - so I don't know what else to do. Is there a way I can force App Store to install a fresh new download?