I’m sure there’s a better, more elegant way but I can’t think of one right now, so try this:
Option-double click on Background to make it a layer. Duplicate the layer. Transform (Command-T) and in the Y field at the left of the Options Bar enter 80 px. Select All/ Layer>Align to Selection> Bottom.Deselect. Command-click on the transformed Layer to make selection. On original layer, Delete. Trash transformed layer. Command-click on original layer, Image>Crop. Done. Flatten if necessary, save, etc.
Canvas Size…
Be sure Relative is checked, and input -80 pixels for the height. Anchor the canvas in the upper-middle position. Hit Proceed to the message that comes up. Of course, make an Action if you have a lot of images.
Carl.