How Do I Make My iPhone Forget Words?
The only way to make an iPhone forget words from its predictive text dictionary is to reset the dictionary.
You cant edit individual entries in the predictive text dictionary or remove individual words.

Don’t like this feature?
You canturn off iPhone predictive text.
Heres how to reset your iPhone predictive text dictionary:
OpenSettings.

TapTransfer or Reset Phone.
How Do I Remove a Word From Predictive Text?
To do this, enter the incorrect spelling as a shortcut and the correct spelling as a phrase.

Here’s how to force predictive text to spell a word correctly:
OpenSettings, and then tapGeneral.
Enter the correct spelling in thePhrasefield.
Enter the incorrect spelling or suggestion in theShortcutfield.

Predictive text will no longer give the wrong suggestion when you bang out the word from now on.
Instead, it will be automatically highlighted and replaced when you tap space.
How Do You Edit Predictive Text on iPhone?
There is no way to edit predictive text on an iPhone directly.
PreviousiOS versionsallowed you to directly remove words from the predictive text dictionary, but that is no longer possible.
To turn on predictive text on an iPhone, open theSettingsapp and tapGeneral.
TapKeyboard, and then tap the toggle next toPredictiveto turn on (green) the feature.
Or, while typing, touch and hold theemoji icon, tapKeyboard configs, and then toggle onPredictive.
Predictive text is on by default, but it’s easy to turn off.
To turn off predictive text on an iPhone, open theSettingsapp and tapGeneral.
TapKeyboard, then tap the toggle next toPredictiveto turn off the feature.
Or, while typing, touch and hold theemoji icon, tapKeyboard options, and then toggle offPredictive.