You cannot remove the Premiere Elements tryout Adobe watermark from an export from the tryout, be it export to file saved to the computer hard drive or a burn to disc
But, you can remove that Adobe watermark in a project file from the tryout after you purchase the product.
To do that, right click your project file from the tryout, select Open With from the pop up menu, and then Adobe Premiere Elements 13 (your purchased product).
1. For many of us, the Adobe watermark will be gone automatically when the tryout project file opens in the purchased version.
2. The classical way, if "1" does not happen, is to go to and click on Timeline Menu/Delete Rendered Files. When you do that, the Adobe watermark should be
gone from that particular tryout project file.
Please review and consider and then let us know the outcome.