How do I remove watermark from PDF on a Windows PC?

I understand your problem. Watermarks really affect the reading experience, especially when learning programming. Fortunately, there are some free open source tools that can help you remove watermarks from PDF. I have tried a combination method before, which is to use Inksscape + Ghostsscript to remove PDF watermarks. The effect is pretty good. Let me briefly talk about this method.

1. First, you need to install these two tools on Windows 11/10:
2. Inksscape: It is a free vector graphics editing software that can be used to edit graphic elements in PDF files.
3. Ghostsscript : This is an open source PDF processing tool that can help you convert PDF to other formats and keep the format intact during the processing.
   Go to the official website (Ghostsscript official website) to download and install.
4. Open Inksscape, click File > Open, and select the PDF file with watermarks you downloaded.
   Inksscape will open each page as a graphic. Find the page you need to remove the watermark.
5. In Inksscape, you can directly select the watermark area and then delete it. The watermark is usually a separate layer or object, so just select it and delete it.
6. After deleting the watermark, you can select File > Save As to save the edited file in PDF format.
7. If you find that the PDF format has some problems after saving it with Inksscape (such as messed up layout), you can use Ghostsscript to fix it:
8. Open a command line window (press Win + R, enter cmd, and press Enter).
   Use the following command to repair the PDF file:

gswin64c -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dNOPAUSE -dQUIET -dBATCH -sOutputFile=output.pdf input.pdf

Here input.pdf is your edited PDF file, and output.pdf is the final saved file name.

With this combination, you should be able to remove watermark from PDF while keeping the document format unchanged. Of course, this method may be a bit informal, but for informal needs, this is already a good solution.