Why do the licensed pictures I have added to my library have a watermark? I need the watermark to be off the images. Thank you.
If the asset has a blue license badge when you download the file or open it from within a Creative Cloud application the watermark will be removed.
In addition to EvilBugQueen1 response, you're still getting the watermark because I believe you're simple saving the previews to the actual file to your library. Previews are low-resolution watermarked version of the actual file.
Please see Stock FAQ: How to license an image with Adobe Stock? to understand the steps for licensing an image.
Also, if you're licensing an image from within an Adobe Creative Cloud application, you'll get a confirmation window confirming for action.
Let me know if you still face troubles.