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If this post or another user's post resolves the original issue, please mark the posts as correct accordingly. This helps other users with similar trouble get answers to their questions quicker. Thanks.
The classical answer for removing the Adobe watermark from the tryout project file (project.prel) is to open the tryout project.prel file in the purchased product and then go to Expert workspace Timeline Menu and click on Delete Rendered Files. For many of us, just opening the tryout project.prel file in the purchased product automatically removes the Adobe watermark. Have you been there and done all this already?
If you can open the program to the Expert workspace, go to the Help Menu and determine if you have a Sign In or Sign Out option there.
Just a reminder, you cannot remove the Adobe watermark from any export of the tryout, whether that export is from burn to disc or a file saved to the computer hard drive.
Please update us on your progress for further suggestions if necessary.