If you are not only the user of your iPhone then you can apply restriction for installing or deleting apps by other people. May be you have purchased an app and you don’t want others to delete it. Below are the steps for the process:-
Press “Settings” icon on the home screen.
Press “General” icon.
Select “Enable Restrictions”.
Enter the passcode and re-enter again to enable the passcode.
Now disable “Installing Apps” and “Deleting Apps” by moving the slider to the left side.
The next time when someone else tries to either install or delete apps then they can’t.
“App store” will be hidden from the screen so a new apps can’t be installed. Also you can’t delete an app.
Note:- In order to make this function effective, you should have Restriction enabled by using passcode.