In Lightroom 11.0, to delete a layer mask, you have to click on the . . . icon and then select delete. However there is plenty of room right next to the . . . and the disable mask button for a trashcan icon. That way you wouldn't need to click into the . . . menu. You could just click on the trashcan icon, which would save you additional clicking and searching for the correct delete option in the . . . menu.