Adact features a cheating detection system but if someone manages to get past it you can still delete such gameplays
Firstly if you conclude that a specific player has cheated, you can navigate to Campaign Analytics and scroll down to find filter of all gameplays.
Once there you can search for a gameplay that you believe was cheated and delete it from the row. It will be deleted from everywhere.
If a person also won a prize then navigate to campaign editor - Prizes - Winners and delete the prize which was assigned to that player as well.
Even if someone finds a way to cheat it's not always negative is no actual harm is done - on the contrary it showcases the effectiveness of your campaign if people are so engaged to try to modify their score in the leaderbaord.
Having said that always make sure you are not instantly giving out prizes which have monetary value incase someone decides to try and cheat!
Always write to your customer success manager when you suspect anyone cheating. We have additional tools to confirm this.