Keywords are used in 2 places.
When you add a keyword to a response, that keyword will be able to trigger that response.
Keywords are also used by the heuristic response matching. When matching the user's input with the trained questions the bot give a "score" to each type of word, nouns and adjective are scored higher than verbs and articles, and keywords are scored the highest. If you have removed all the keywords from the response, then I assume this is what you are seeing.
You can remove a word from being a keyword from the bot's Knowledge page by querying instances of class keyword and removing the #instantiation relationship from the word to the keyword. We are working on having a simplier interface into keyword classification.
You could also just reset your bot's memory and re-import your responses as a response list to clean everything up. In general never make common words like "the", "how", "what" keywords.