When you delete a Keyword, all contacts that have opted in using this keyword will no longer have this keyword group connected to them. If you want to keep the keyword tag - but not let anyone else opt-in to the keyword, try Pausing the Keyword.

1. Click on the Opt-in tab on them left-hand sidebar

2. Hover over the Keyword you would like to delete, and click the trash can icon on the right side of the line

3. Click Delete Keyword on the pop-up