How do I make iTunes capable of deleting from my iPad?
This is a tricky thing to troubleshoot since once the iTunes tracking database or the iOS tracking database gets corrupt - what should sync and work starts to fail.

In the interest of putting out a concrete set of steps, here is how I fix things like this:


Make a quick judgment - should I just restore the iOS device and start fresh or are there things on the device I need to back up and save?
If I need to back things up, now I'm worried my backups might be corrupt too, so run one backup to iCloud and one to iTunes to be paranoid and safe.
Then I spend 5 minutes deleting things I don't need on the phone (calendars, Mail, contacts that exist in the cloud), game apps that I don't care about losing progress or can re-dowload or sync via iCloud.
Test the sync again.
Continue spending 5 minutes paring non-essentials and testing until I'm left with just the really important things on the phone. I then export them or back them up and then erase the iOS device.


Again, it's painful to erase things and start over, but my experience is that this problem is almost always on the iOS device and can be cured by an erase and setting up sync again from scratch.

You could try the opposite tack / work from iTunes and stop syncing things one by one until you find the item or class that is causing issues. I've seen that work too, but it seems to fail to cure the underlying problem and I'll be back in iTunes micromanaging the sync settings in a week or a month so I now go for the erase / reinstall option.

The benefit of an erase install is that you test your backup and you have the chance to examine the things you care about / ditch the cruft that is on your phone. Rather than being forced to learn if your backup works when you lose a device or break it - you will learn now if restoring works and have chosen the time to test your restore.

Good Luck - hopefully you don't need to go all the way to erasing and setting up a new phone, but if you do and it fails, you can look squarely at your iTunes to blame for the issue.