Open the extension by clicking the Delete Facebook Posts, Photos, etc. icon in the top right of the browser window.
Click the Go to Facebook button to load the facebook activity log.
At the facebook Activity Log page, open the extension again by clicking the icon in the top right of the browser window.
In the box labeled Text Contains, enter then name of the group that has the posts you want to delete.
Click the Yes, Delete Activity button to start the removal of your facebook activity.
Wait for the extension to delete your facebook posts and other activity.
See the status of the facebook items processed.