sudo apt-get install pdftk pdf2htmlex

#remove DRM
pdftk input.pdf output output.pdf

#Remove DRM and Password
pdftk input.pdf output output.pdf user_pw YOURPASSWORD-HERE

#convert pdf to HTML without losing formating
pdf2htmlEX output.pdf

#file is not an html file named output.html
#you can now edit this and if you want print it back to pdf
#<html xmlns="http://www.w3.org/1999/xhtml" contenteditable="true">

sudo apt-get install qpdf
qpdf --password=<password> --decrypt input.pdf output.pdf

####NOTE####
#to edit pdf directly use flpsed
sudo aptitude install flpsed