How can I remove the coin doubler without reinstalling the game and losing my progress / downloaded characters?
I'm hoping to be able to remove the coin doubler I bought a long time ago, but I don't want to lose my progress and downloaded characters. Is this possible?
You don't, and you can't.
Well, not without using save editors anyway...
You may be asking...
Why?!?
This is because of the way saves are implemented. On both iOS and Android, saves are tied to each device the game is played on, and that the status of whether or not a save has a coin doubler (like Jetpack Joyride) is in the save file.