This app is the only app that I have found that deletes your messages without crashing the phone. You tell it to delete old messages (2 months, 1 month, 2 weeks etc) and it begins deleting. It starts with the oldest so you dont have to worry about losing recent texts. Also it shows you the progress. Over about 3 nights of leaving it on (you can cancel whenever and continue later) I deleted over 7000 texts! Hope this helps someone. Edit: Wasn't very clear, the app is called "Delete old messages"