AT&T 7406BIS - Manual (Page 42)

To cancel a Leave 1 Press [ Cancel LWC ] (while off-hook)
Word Calling message or dial Leave Word Calling cancel code (while off-hook)
(you cannot cancel [dial tone]
messages for an
2 Dial extension [confirmation tone]
AUDIX subscriber)
●
Message is deleted
Note: If reorder tone is heard, message is not deleted;
try again.