...
Click "Settings"
Select the space that you want to hide the watermark in the pop-up page
Select the page that you want to hide the watermark
The "Select All” and “Deselect All" function can help you quickly pick the pages
Click Save/Cancel to make the above operation effective/ineffective
Click “When creating a new page” to select Hide watermark, so the newly created pages will not display watermark by default