So here are some screenshots. Youll need your msl.
Im not responsible for anything you do in your life.
Highlight the alert field there and click 'edit entry'. 'Active service' will make that alert appear in the messages app under settings and the 'selected' field represents the alerts 'on/off' status. So you can uncheck 'selected' to disable the alert or uncheck both boxes and remove them completely. You can go back after removing and disabling them and read from phone again to see that they are in fact disabled.
I hope this helps. Worked for me. Make a nand regardless. I really didnt want those alerts there and Im glad theyre gone.(the only proof being if one is sent and I dont get it, I guess)
If this is known, well...