I wanted to take all the Desura games off my collection since it's mostly duplicates of what I have from Steam and/or other sources, and Desura seems pretty dead these days.

I managed to get as far as showing all the Desura games in my collection only and selecting them all, but it didn't seem to work when I tried to delete them.

I haven't been able to recreate this one. Could you set up your scenario again and post a screenshot here (whatever you have, so filters, items checked, etc) or send me one in Steam? Also, what browser are you using?

I'm on Firefox. I'm able to get the filters to where it's only showing my Desura games. I click the Select All checkbox. From the nearby Edit Selected dropdown menu, I select Delete.

A window comes up saying "Remove from Collection" with the options Cancel and Remove. Clicking Remove seems to do nothing.

You should be able to see the screenshot at https://www.dropbox.com/s/kq2msvaimne0pcv/Screenshot%202019-03-09%2011.22.34.png?dl=0

Ah, I see what's happening. The shelf view doesn't have the hooks for the bulk actions. I must've forgotten about this when moving things around with the UI revamp back in January. I'll have to see if I could provide support for bulk actions on the shelf view. Unfortunately, shelf view is a completely different UI component and I'm not even sure off-hand where to put a checkbox on the individual items. In the meantime though, if you switch to one of the other views, bulk delete should work.

Okay, that worked. I had to unselect any games that were part of compilations (but not the compilation itself) before I hit Delete, but it worked.