Kodi 18.01

Hi People, I am new, keen and willing to learn, have had kodi Jarvis 16.1 for a while and enjoyed it, but I could not resist trying to download Kodi 17 Krypton, in my excitement I downloaded Kodi 18.01 Alpha 1 and although some of it works and like the concept I am paying the newbie price for downloading a nightly instead of a stable.
I have tried several times to delete it and looked at different ways to do it but none work, when I reinstall it always comes back to Kodi 18.

My question of help is how to step by step totally delete it and install Kodi 17 stable, I have followed the steps on the official site but nothing seems to work, I am determined not to give up, is there a clean way to do it and succeed?

Thank you for listening to a newbie.

The Gowk.
(an old Scottish word for a daft man)