Hehehehehe, I also went over Lvl. 700 cause I fell asleep... Anyways, You can't get back down on levels but if you don't play for 2 days straight you won't be on the ranking leader-board anymore, then again if you start playing after you'll get in the rank...
I think you are safe though, If you want to avoid the ban hammer, turn the mod off for all other mode except the main campaign. No boss, specially no Journey & PvP...
For new account, In iOS, Just use your extra apple ID and log in to "Game Center" with that, or create another apple ID and log in to game center using that, Reinstall the game again and all done... @skyz777
Good Luck...
@DanYal Thanks for the update mate... You are the boss... 😊😊😊