The watermark can be deactivated via the application settings file, which is in:
You will need to find the following settings, and set them all to false,
then restart the webapp for it to take effect:
# When to apply the watermark:
Please note: as thumbnails are generated when images are added to Asset Bank, changes to these settings will not affect images that are already in the repository. However, you can regenerate thumbnails for existing images, if required.
If you would like to change your watermark, please see our configuration help.