Delete pdf files?

Hey can someone please explain to me quickly and quickly how to delete pdf files? So I got in my email my certificate with pdf and have too many pages (7th class I do not need) And I want to delete 4 pages but how does it work if it is pdf? Have a laptop, acer.

Like any file, remove marking or delete right mouse click

Quite simple

Or it is 1 PDF file then no chance you would need a professional and paid for example. Adobe Reader DC access.

But why? When printing, you just part in two and leaves the four away