One cannot make changes of the iphone account on the iphone itself. For one to know how to change itune account on iphone the user needs to connect to connect their iphone to iTunes. One requires a personal computer connected to internet. You can then access the Apple website where you access the iTunes store which is found on the horizontal menu at the top. You should then go to the account option on the menu and log out of the iTunes account.
While still on the account option, using a mouse click on the account information and create a new account by keying in the details that you wish to use with your iphones and iTunes. The iphone should then be connected with the personal computer using a USB and allow it to sync with your personal computer. If the changes on the iphone are not made, one can opt to download a free app from iTunes store with a new identification details in it. Once the downloading is complete one should sync the iphone again and try to delete the app. The two procedures when carefully followed assist one to be aware of how to change iTunes accounts on iphone.