Select all faces at once

[frankdarwin]

Is there a way to select all faces in a photo at once to delete them all?

[Asgard]

I don't think so but it would be a nice addition. I already have it on my list of things to propose as feature additions.
In my case I would like to be able to Ctrl-click to select multiple faces, and possibly Ctrl-A for all images, and then copy to the clip board and paste to a similar image.

[abgestumpft]

In the viewer this is already working:

Ctrl+A will select all faces
Shift+Click you can select/deselect several faces
Ctrl+C copies the marked face annotations
Ctrl+V inserts the copied face annotations

[Mario]

See: Selecting Annotations, Clipboard Support or, in general, the detailed Annotations help topic.
Faces a just one kind of annotations IMatch supports.

If you wonder if something can be done, I recommend to check the corresponding help first. This will save you some time for sure.