Click on the small icons above each individual look image to edit the Look, remove the Look image, or delete the Look (as with most places in the system, hovering over each icon will tell you its function). 

Edit multiple Look images by holding the Shift button on your keyboard and selecting the images you would like to edit.

Click “Clear Selected Images” to remove the look images associated with the looks you have selected.

Click “Delete Selected” to delete the entire look(s) you have selected (i.e. the images and the look numbers).