how can I remove all evidence of cookies related to "Grammarly"

I am trying to use these instructions for Mozilla Firefox to clear all Grammarly cookies 1. Click the three horizontal lines (menu button) in the top-right corner and select Settings. 2. Choose Privacy & Security from the left-hand menu. 3. Scroll down to the Cookies and Site Data section and click Manage Data... 4. Type "grammarly" in the Search websites field. 5. Click Remove All Shown and then click Save Changes to confirm. [1, 2]

but my settings page doesn't show Privacy & Security