If you're on PC you can just hover over the save file and hit the "del" button on your keyboard :)
If you're on Android you'll have to manually delete the files from the save folder, which you can find here:
Android/data/com.domain.corruptedkingdoms/saves
NOTE: If you're running Android 11+ then Google has hidden your data folder. To access it you need to connect your phone to your PC with a USB cable or use an app like Solid Explorer or X-Plore to give you access to the folder again.