Text management in iOS

I am trying to delete a system-installed text replacement (Settings ->General-> Keyboards-> Text Replacement) snippet, and having no luck either doing it or finding anything in the support library. I use “ T M” (without the spaces, thank you very much) a lot for something I do, and the system automatically changes that every time I type it. I need to delete this entry. Can anybody tell me if it’s even possible, and if it is, how I do it? Thanks in advance.