Once a sale has been created and activated, you would not be able to change the effective dates or cancel the sale from your end. Biblio will often highlight a seller's book sale in promotional emails which are sent to many thousands of potential customers. In addition, Google product feeds can take up to 48 to update. We don't wish customers to be disappointed by seeing a lower price in a Google search or a promo email, and then find a higher price on that same item when they link through to Biblio.
If you set up a sale that you need to cancel early, just email us at email@example.com and we'll get the sale canceled within 48 hours. You can then create a new sale with different parameters if you wish.