Assuming you do own right to documents, then it is simple work on Watermark On Pdf . Go to Edit PDF, And that all there too it. Likewise, you can do it on Watermark On Pdf to remove textbox once you go to Edit PDF within Watermark On Pdf . If you are asking about locked content or copyright contents you do not own right. Then you can not ask this type of question here.
In addition to this, some PDF books can hide information. For example, an e-book book can show only the first 10 pages. A scanned copy of a book may still show its contents. However, you can prevent people from reading hidden pages by using watermarks. You can add watermarks using the 'Create Watermark' menu option. I found that the image in this example looks too dark, so I simply added a watermark to the top and bottom of the document. This makes the image more visible to the eye. Adding Watermarks to a PDF Page You need to first add a watermark. Click on the 'Get to work' button 'Add watermark' option (the square, white checkmark icon). Click on the drop-down box to choose your type of watermark (or select from the drop-downs box). Click on 'Add Watermark' and confirm the options. If you want the document's title, author or the page number to be displayed, click.