Maybe I'm missing something, but it appears impossible to delete more than 1 fixture at a time. From both Tile and Table views.
Press and Hold the magic "Select All" group, a context menu will appear showing "Delete Offline"
If a group has been made with the devices you want to delete, Press and Hold (Context Click) on that group: a context menu will appear showing "Delete Group and Devices".
Thanks for this! I hadn't thought to try that.
Now that I know the secret handshake: Delete Group and Devices crashes the app in Table view
Oh Interesting! I'll write that up and have that fixed shortly.