Disable automatic transferring!

The content of your iPhone reflects what you have loaded to your iTunes library.

To stop updating, plug in phone, Walt until is done with update process or when exits out with device full message, then go into iTune's iPhone menu and disable AUTOMATICALLY SYNC, but this won't erase anything that's already on the phone.

To clear stuff on the phone u have to do media management to iTunes, deciding what in iTunes U want to sync to phone and what not. Then once that's done the next sync will remove all media from phone that u told iTunes not to sync.