A technique I've used in the past that usually works well:

Right-click the page and hit "Inspect Element". Scan through elements, looking for the ones that only refer to the header or footer stuff you don't want. Click them and hit "delete" on your keyboard.

Find the container that defines the width of the content you're viewing. Use the style editor to reset it to 100% (often, it's just disabling whatever width setting they're using, rather than explicitly setting it to 100%).

You should be able to CTRL+P from there and get yourself a PDF out of it. Then you can do whatever you want to the PDF. I think you could also just save the raw HTML, and the browser will preserve your edits.