Remove watermark preset with on or off once images have been uploaded.
You can now make changes, add or remove watermarks right from your dashboard without having to re-upload your images. Simply go to the collection, select one or more images you’d like to make this change to, and click on the “Watermark” option under the “More” drop down menu.
Learn more: http://support.pixieset.com/knowledgebase/articles/1169314
Other Watermark updates: http://pixieset.tumblr.com/post/160482083880/new-watermark-features-added