Hello,
The Find and Replace utility in the Edit menu can batch remove unwanted keywords. The Find field will have the keyword you wish to remove from the selected group of images. The Replace field will be empty. The Metadata box needs to be checked in the Searching section. Check the Keywords box in the IPTC field list. My test example also has the Case sensitive search and Treat repeating fields as single string, boxes checked. I have attached a screen shot of this configuration.
regards,
--Bob