Yes, there is! In the Search, you query the word and then use Edit Post to select all mentions and then delete them.
Search: Filter your posts by the keyword by entering your word and clicking Search.
After the monitor reloads, click on the Dashboard icon to the right of the search bar to open the mentions feed.
If you'd like to view the mentions feed full screen, click on the double arrows icon.
Select the number of Results Per Page: 100, 500, 1000 mentions per page
Edit Posts, check the Select All box and then click the delete icon (red trashcan).
Depending on the Results Per Page you select to display (default is 100 mentions per page), that will be the number of mentions deleted.