I have this same issue. When I installed Ababtecart I included the demo data to get a feel for how things worked. I have now added a bunch of my own products and changed a number of things so don't want to do a fresh install without the demo data.
I cannot find a menu option to bring up the Resource Library so I get to it by editing a product, clicking on the big + sign to bring up the media manager then clicking Resource Library link in the top right hand corner. It would be nice to have an admin menu item for this.
Once I do this if I select an item and then select Delete from the actions drop down it states "Cant delete resource(s) because one or more resources is linked to object". However, if I select "Unmap from Object" in the drop down, I get a bit of an animation of lines like it is doing something, then I try to delete again but get the same error message about the image being mapped to an object.
Oh, and I had gone through and deleted all the demo products and categories, so there is nothing there for the image to be mapped to.
Bug?