How to Enable Restrictions on Your iPhone
If you share your iPhone with another person (or you're a parent or guardian who holds the keys to iPhone's kingdom), you can allow or restrict access to apps and features, or block access to content, such as songs containing explicit lyrics, or movies or TV shows based on their MPA rating.
You can also allow or restrict changes to specific apps such as Contacts and Calendars as well as accounts. Scroll down to list to find a Volume Limit setting and Game Center limits.
To activate and adjust iPhone's restriction settings, tap Settings→General→Restrictions. Tap the Enable Restrictions button and then type in a secret four-digit code, and then type in the code a second time to verify your code. Tap the apps and features you want to turn off or on. App icons for any apps you restrict disappear from iPhone's Home screen.
Although you'd think turning off access to a certain app such as Safari, for instance, totally blocks your iPhone from accessing web pages, that isn't one-hundred percent true. Although the app icon disappears from the Home screen and browsing the web with Safari is therefore disabled, certain apps you may have installed on your iPhone can still access the web using their own web browser features.
For instance, tapping a web page link that appears in the Facebook, Twitter, or Google apps opens those apps’ built-in web browsers to display the content of a web page link. There are also other browser apps, such as Google Chrome, which can't be restricted with this setting.