How to disable Instagram and Tweeter rather than restrict time usage?

Hello, gforce_xxx!

Thanks for reaching out to the Apple Support Communities! That's a great question you have about disabling apps on your device. Check out this article to Use parental controls on your child's iPhone, iPad, and iPod touch:

"Allow built-in apps and features

You can restrict the use of built-in apps or features. If you turn off an app or feature, it won’t delete it, it’s just temporarily hidden from your Home screen. For example, if you turn off Mail, the Mail app won't appear on your Home Screen until you turn it back on.

To change your Allowed Apps:

1. Go to Settings > Screen Time.
2. Tap Content & Privacy Restrictions.
3. Enter your Screen Time passcode. 
4. Tap Allowed Apps. 
5. Select the apps that you want to allow."

Thanks again for the question and have a great day!