LG Shine CU720

So I got a new LG shine for my wife for Valentine's day. She loves the phone except one thing... The phone does not appear to have an auto-delete function for text messages. Most phones I have had are either already setup to auto delete the last text message so as to leave room for new messages. Or there is a setting that can be changed to allow for this to happen.. I imagine that it is probably not an issue for someone that rarely text messages but that is not the case in my situation.

I bet there is just something that we have both overlooked..

I am desperate! Let me know!!