Not allowing apps to download I want to permanently delete twitter and facebook off of my iphone6s because they are a constant distractions.

is there a way to delete a given app and then not allow it to be re-downloaded at a later date?
This won't do exactly what you want, but you can make it harder to reinstall them using Restrictions.


First of all delete the apps
Go to Settings > General
Tap on Restrictions 
Enter a restrictions passcode
Toggle the Installing Apps option to disable it
Exit Settings 


This will remove the App Store from your Home Screen and means you won't be able to install anything else without having to go through the above steps again and toggling Installing Apps back on at step 5.

It's a major nuisance, but maybe you can use this restriction for long enough to break your habit and then remove the restriction later! I've read that in many cases 21 days is long enough, although everyone is different.