Delete Layer Mask

If you decide, for some reason, to get rid of layer mask, drag the mask thumbnail* onto the "trash" (screenshot).

*If the layer (with the mask thumbnail) is hidden inside a group, open the "Masks" dialog and apply the "Delete Layer Mask" command.

There appears a dialog box suggesting two options:

1. The "Delete" button just removes the mask (that is, reveals the entire layer).
2. The "Apply" button removes the mask and clears the hidden areas of the layer.

Let's make it clear that the both choices are "destructive". You can restore neither the mask nor the cleared fragments of the layer.