Deleting old PDF versions of reference in Endnote X8

I would like to delete single old verison of full text PDFs in my Endnote X8 (Mac) library. 
Unfortunately, I haven’t found any way to do that unless if I go into the single folders through Finder and delete them one by one. 

Any help would be greatly appreciated.

If you look at the bottom right corner of your screen capture, you are in the “Preview Panel Not Visible” view of your record. This just displays the PDF files. Click the “All Panels Visible” or “PDF Panel Not Visible” display option for the record. This will display the contents of the record including the Author, Year, Title, etc. Scroll down until you find the File Attachments field. Delete the attachment you want to remove, then Save and Close the record.