Messages won't stay deleted- iPhone 4s, 7.0.4
Hi everyone! Looking for help for a problem I've had for a really long time. My messages in my iPhone are taking up most of my storage space. Most if not all of the messages are irrelevant, and I want to delete them all. They go back approximately 3 years, so it's a lot. Everytime I try to delete individual threads, the app freezes and goes blank white, and won't allow me to send or receive messages until I restart my phone. When I restart, I can send messages again and the messages I tried to delete are all back.
Also, my iCloud is full, so please don't add a solution that involves a backup to iCloud because I can't do that until the messages are deleted.
Thank you so much!
iPhone 4S, iOS 7.0.4