As a short term solution, you can use netguard and always have it run in lockdown mode. It works on most phones and doesn't require root. You can use it to whitelist app access to the internet (inc. blocking samsung and google play updates). It's also open source.
In the long term, just avoid samsung products that don't respect your authority as the owner.
Samsung has followed suit w/ Android. Once an update is available, the user can defer it three times before the phone is rebooted. Not even Apple pulls this crap.