help with a txt message undo

[Mike_323]

how do I undo a sent text message on my non-smart cell phone? help!

 

[antoine21839]

how do I undo a sent text message on my non-smart cell phone? help!

You can't. On smartphones, if you remove a message, it will only be client-side (only removed from your phone).
You can flood the chat with random letters, but that's kinda barbaric (and it still does not removes the message).