Galaxy S6 :: How To Delete Stock Keyboard Predictive Text

I've been trying to figure out for weeks how to remove things from the predictive text dictionary. All the instructions I've found have had some version of long-pressing on "Predictive text" in the settings menu, but all that does for me is toggle it on or off. It doesn't open a new menu. I don't want to turn it off completely. I just want to delete my personalized typing history.

Two other things I've already tried with limited success:

Long-pressing on a suggested word so that it says " 'X word' will be removed from learned words" works for that specific word about 75% of the time, but it still sometimes continues to come up as a suggestion, and it only works on a word-for-word basis. I want to delete my entire history.

Going to the application manager and clearing the cache and data for the keyboard app deletes all of my personalized settings and appears to clear the text predictions for my SMS texting app, but it does not seem to clear my typing history for non-Samsung apps. Specifically, I use Aquamail to read and write emails, and I can literally rewrite an email using the predictive text on my keyboard.