Yes you can! The items must be in your Listings page in order to do this. Go to your Manual Listings page.
Select all the items you would like to mark (or Select All). Once you have selected the items, scroll down and click "Sold Selected Outside of Sonlet."
This will take you to a page you can enter the information for all of the items selected.
You can select a Recent Order, a Previous Customer, or enter new Customer Information. Only the Name field is required for new customer information. Be sure to click Submit to complete the sale. The items will then be moved to your Sales page.