MissB:
If you're using a computer with Windows10 it's fairly easy to do, although it might be time-consuming if there are a lot of pages you want to extract.
With your PDF viewer on a page you want to keep, make a note of the page number, then select 'File⇾Print' and choose a printer called 'Microsoft Print to PDF'.
Where it says 'Page Range' click the button next to 'Pages' and in the box next to it, type in the page number. If you want each page in a separate file, click 'Print' and give it a file name before clicking 'Save' on the lower right.
I believe it is possible to print multiple pages into the same file by entering multiple page numbers separated by commas, i.e. 112, 216-218, 804
RopeFiend is right about PDF Exchange, but only the paid version allows extraction of individual pages. I use the free version and use the method I've described to save individual pages.