how to delete photos ?

After importing a video sequence, I want to remove those images in the video that don’t contribute to the reconstruction instead of having RC do useless computations on them.
It is quite inconvenient and time consuming to click the delete symbol for each photo.
Why isn’t there a button to remove (or better: disable) the selection from the thumbnails view (2Ds)?

Then I’d like to physically remove those images from the project BEFORE any alignment takes place.