Managing files can be very exhausting when you have too many files to deal with.
A good file explorer and manager is, therefore, necessary to reduce the hassle.
This free software is a file manager for anyone who owns an iOS machine.

tap on any category and it wont take long for you to be able to see its contents.
Say, for example, you punch the Music category.
Every title has a checkbox next to it.

To delete a file, snag the file, and smack the Delete button icon.
iFunbox can transfer files between your PC and iOS gear.
you could remove any app that you dont need anymore directly in iFunbox.
you might also install a new app if you find one that you really need.