[dw1]

If you can't edit it with Adobe Acrobat Pro (latest version) or Bluebeam, then it's likely the file is protected and you'll have to find a good utility to crack the protection. Depending on the level of protection, this can be either relatively straightforward or next to impossible.

As you mentioned it was an on-line .pdf, odds are it is fairly well secured.

Remember that Adobe Acrobat is not a file format like MS Word or .txt files that can be easily edited, but is a "electronic printout" that was originally meant to be open to being annotated, but not edited.