Do it with a computer. I found a PDF with password and digital signature. Many tools can handle passwords, but there is really no tool to delete digital signatures.

The method is to remove the password first, and now you can copy the content and print it. However, because the digital signature still exists, it still cannot be modified and annotated. I tried to print this document as a PDF again, but the digital signature disappeared, and so did the bookmark of the original document. I saw someone on the Internet saying that "extracting pages" can achieve the same effect, but it is also impossible to extract bookmarks together.

Finally, I found a solution online:

1. Create a one-page PDF and open it with Acrobat.

2. use "document->; Insert page ",insert a digitally signed document at the back of the page.

3. use "document->; Delete page ",delete the first page, and then save the document.

This method can not only keep bookmarks, but also completely remove digital signatures, and it is simple and easy to do without special software.