LDFtp‖Delete Comment

QPL3j‖Deletes the comment of the cell.

To access this command...

ebLJB‖From the menu bar:

fDua6‖Choose Sheet - Cell Comments - Delete Comment

t8dFS‖From the context menu:

UuXES‖Choose Delete Comment.

qBbLh‖From the tabbed interface:

BbB2Q‖Choose Review - Delete Comment.

sXy2C‖From toolbars:

irMeE‖Icon Delete Comment

NYhJA‖Delete Comment