unauthorized admin hacker on all my family devices thru nearby controller help

change your passwords to a safe one on your account(s) and remove all apps not installed by you or to ensure a clean device, i would recommend a wipe and reinstallation (after backing up everything needed). If an account is used on multiple devices i recommend to wipe all of them before reinstalling any of them to ensure no sync does happen.

And never download/use apps from unknown sources to prevent such things from happening.