How do I get rid of saved messages on iOS7?

Thanks but as I said in my message above, I tried deleting them from there and when I restart they all reappear and the messages allocation in Usage only went down by a few points cuz nothing was really deleted. I need to know why deleting them from iMessage isn't working and how to delete them permanently.

So after doing some research online, it apparently is possible to permanently delete these but only after syncing with iTunes. All the articles I found on it were written before iCloud was invented but I'm guessing it's the same process since iCloud would back up whatever is on the phone currently thereby deleting messages which have been marked for deletion (that's essentially all we're doing when deleting them from iMessage). I haven't actually tried this method yet but I will today and get back to you all with an update.

If this doesn't work, then it's time for a trip to the Genius Bar. Stay tuned...

They're marked for deletion when you delete in iMessage but won't actually be deleted unless you sync with iTunes (or possibly back up to iCloud but I have yet to test this out). If you restart your phone, you'll see all your deleted messages return to iMessage. It's quite frustrating that they can't just be permanently deleted when you press the button. *sigh*

Yeah, my friends' and family's iPhones aren't experiencing this either. My guess is that in an interrupted sync, some corrupted data got stored into messages so it would generally be a localized issue. And it also depends how much media you send in text messages. I, for one, send a lot so it makes sense how it would have gotten that high, corrupted data or no corrupted data.

Ok guys, I found a weird work-around for this. Apparently, if you delete one conversation in iMessage and then back up to iCloud (or iTunes), it WILL delete that conversation and free up space. However, if you try to delete more than one conversation and then do this, it won't work. Once you restart they'll all be back. So it is a tedious process to delete one conversation at a time, but if you can pinpoint the ones which you know have a lot of attachments in them or something then just try deleting those one at at time and backup the phone. This works for me and I now have 4GB of space recovered just by deleting two conversations!!

Very buggy feature though since it doesn't work for more than one at a time but at least there IS a solution! Let me know if this works for you all.