Can I delete the ads from a game?

try using lucky patcher if ur rooted or adguard dns

Check out PiHole (https://pi-hole.net/) as it blocks the domains of known ad companies (and tracking sites) and means that they won't load on any of the devices on your network at home

If you turn off your internet, you will not see any ads. If game needs internet, it's not possible.

You can install firewall app on the mobile phone and stop specific apps from connecting to internet. This will help you from seeing ads but that will also block all the online only features.