I know of no way to remove words that are already in the dictionary. Only words you may have added yourself. You can, however, turn off predictive text, which then will give you no words and you must type everything out yourself.
How to turn on/off Predictive Text/Text Suggestions.
Depending on your device, and android version, there are a few different ways to turn this option on/off.
Option 1.
1. Go to "Settings" and then tap "Language & Input".
2. Next tap "Default" (keyboard) and then tap your default keyboard.
3. Now tap "Configure Input Methods" and then tap "Settings" next to the keyboard you are wanting to alter.
4. Here tap "Text Input Settings", then tap "Word Suggestions".
5. On this next screen tap the option you wish to have used.
You should now have/not have the suggestions bar, depending on which you chose to change to.
Option 2.
1. Go to "Settings" and then tap "Language & Input" (it could also say "Language & Keyboard").
2. Next tap "Android keyboard settings" and check/uncheck "Show Suggestions".
Option 3.
1. Go to "Settings" and then tap "Language & Input".
2. Next tap "Google Keyboard" and then tap "Text correction".
3. Slide the "Show correction suggestions" and move the switch to the right/left to turn this on/off.
Option 4.
1. Go to "Settings" and then tap "Language & Input".
2. Next tap "Keyboard & Input Methods" and then tap your default keyboard.
3. Now tap "Text Correction" and then locate "Next Word Suggestion" and move the switch next to it to the right/left to turn this on/off.