If you want to change the List you saved your Keyword to, then just head over to the Lookup tool to make the change.
- Type go lookup then into your address bar then hit Enter
- Search for your Keyword in the search box at the top of the page
- Find the keyword you want to move into another List
- Click on the pencil to edit the row
- Use the drop-down menu to select the List you want to move the Keyword to
- Click on to save the changes, and you're done!
Just keep in mind that by changing the List a Keyword belongs to means members of the original List may lose access.