Today I posted a big stack of books and accidentally included six I was holding for my sister. These are brand new books and all wishlisted. I saw my mistake almost right away, but cannot remove them from mys shelf beacause all are on hold pending wisher's confirmation.

I don't want to wait and disappoint each of these people one by one by canceling the transaction after it's been accepted. Isn't there anyway I can correct this immediately?

Deleting from the shelf isn't an available option. The only feature is "mail to a friend". I tried that but it doesn't actually work.

Ideas?

Unfortunately, you'll have to wait until the requests are accepted and then cancel.

You might want to write a really strong apology and PM the folks.  Letting them know that you are going to cancel.

If you put your account on vacation-it'll stop any that time out from being offered to the next person in line.  But with the ones already pending-you will have to wait for it to be accepted and then hit the I Cannot Mail For Other Reasons button.

Mary beat me to it.  Put your account on hold to stop the loop!  She gave you the right advice. 

I've been on the other side of this in the past.  Once accepted, just send a quick message to the recipient to let them know it was an accident.  Hopefully, they'll be understanding, stuff like this happens.