Try sending a reply message to the sender w/ the word "quit" or "stop". That will usually do the trick. If that doesn't work, call you cellular provider to see if there is some type of subscription service on your account that can be deleted by them.
Hi, We have a LG600G cell phone with net10. Once in a while we'll get a message about a weather forecast somewhere. We're in California and just got a weather forcast for New York. It uses up minutes. Can we stop it? How did we get on a list for it or what? Any ideas?