You can add/amend/remove Keywords from the Daylite preferences window.

From the menu bar select Daylite -> Preferences...
In the preferences window select Classifications -> Keywords

The +/- buttons add/remove keywords.

When adding a Keyword, ensure that it applies to a object i.e Contact, Organization, Opportunity or Project

If you prefer to keep a Keyword, but would like to make it temporarily inactive, simply uncheck the 'active' boxes located to the right of the keyword names.

Please note that active checkboxes have to be checked for you to use them.
Also if you choose the delete them, you will be asked to replace existing objects with this category to a different one.