Permanently deleting imessages on iPhone 5?

Hi,

I see ios 7 is keeping a 4 gb file of my imessages and I have seen various methods to delete them off the phone including restore, or using ibackupbot etc.

I cleared the imessage cache off my phone six months ago after searching for a solution for hours. I finally found a solution in a forum that did not require restoring, external app, or other extreme methods . I just can't remember the method. Can you help?

Method

Found the note and just got about 11gb back on two iPhones and iPad.

Method is:

Turn off iMessages
Uncheck iMessages in spotlight search settings
Delete messages in iMessage you want to permanently delete
Kill all running apps in background
Reboot
Turn on iMessage

I'm surprised this isn't the top solution in the apple discussion forum. I don't remember where I found it but it saved me $40 for app that does same thing. I can now download movies on my iPad.