Game reset issue

Hello everyone!

First of all sorry for the little stupid topic but..

It's about the game Tiny Heroes 2. Everything looks pretty cool there, however I have this issue. I wanted to start the game over, but I can't find an option neither in the game nor using the phone settings. I think the game is not connected to the Game Centre, it's only connected to the Apple ID... Can someone please explain how is it possible to delete the game data and start over?? Thank you in advance!