An attachment to the work object is stored as an instance of "Link-Attachment" class and it has a reference to the work object and the attachment. You can delete the reference and the attachment.
You can write an activity to open the instances of "Link-Attachment" class by Obj-Browse/Obj-Open(Refer them:- Obj methods in Pega and Useful details) as per your business requirements.
I ain't sure about an OOTB activity for this specific requirement.
Hope it helps you in addressing your business requirement. Kindly notify if it does by marking this post as answered for larger Pega audience and tracking purpose. I would keep you posted if I get specific activity.
If we delete Link-Attachment, the attachment gets disconnected from work object but still remains in the DB as an orphan record right? What all records need to be deleted in order to avoid orphan attachment records.