This cannot be undone! If you want to offer the book for swapping after you have deleted it, you will need to repost it to your account Bookshelf.
Note: If you have clicked "I cannot mail" on a request, or clicked "Cancel" on an active outgoing transaction, or the system has canceled your transaction for failure to complete the sending process by the deadline, the book involved will have been automatically removed from your account Bookshelf.
Related links:
What is My Bookshelf?
Can I put my account Bookshelf on hold/vacation?
What does *pending request, 1 hr max* mean?
Can I post multiple copies of the same book?
Can I send a book to a friend?
How to post a book
Posting and Sending a Wish Listed book