How to reset all iPhone app games?

I just want to know how to reset all of the games on my iPhone so I can start them all over again.

First you need to store your apps in itunes in mac or pc, after that reset all settings and copy your apps to your iphone. Apps and games are start over

As in resetting the save files? Or deleting all the apps on your phone?

Start by making sure all your apps are synced to the App Store, then you will want to reset your phone and download all the apps again. Most, if not all should be reset.
(I say most because some apps have specials ways to store like rovio, where if you make an account your data is truly saved forever.)
Hope this helped!

Delete & reinstall.

Not all games would be able to do that though since your progress is saved on servers that you can't access.

I would suggest remove and reinstall for local saved games while create a new account for online-based games after game is reinstalled