How to stop Samsung Keyboard from learning the words I typed?

Samsung keyboard learns the words you often type through the Predictive Text feature. On some models of phones, the keyboard come with the Personalized data option in the Samsung keyboard settings which you uncheck to disable the word learning.

The newest models very likely have the Personalized data option taken out. In that case, you’ll just need to turn off the Predictive text option to disable the word learning.