@Jo
I think it should be a no-brainer for the devs to add a "delete image" button to BSS's image browser. I've mentioned this before in the Ideas forum, but it was lost to the sands of time. I don't think it's even mentioned anywhere in any of the tutorials that you can right click on an image in the Design > Images panel and choose delete. Just like there's no specific mention of how to make a new page. They finally stuck it in the top menu under File > New Page, which is probably the last place a new user would look, since creating a new page has nothing to do with file activities.
My frustration is building. I'm going to take the problem of this program's abysmal documentation into my own hands soon. Just gotta get caught up on client work.