Hi Hans,
On Windows this is quite easy: just run the installer or use the Control Panel.
Mac is a very strange OS which has no real concept of uninstall, so you will have to do it manually. And even more: Apple in all its wisdom often decides to change new versions of Mac OS so that old uninstall scripts no longer work. And even better, Adobe changed the location where plugins should be installed, complicating things even more. If I'm not mistaken, the latest incarnation requires this convoluted way:
1. Using Finder, navigate to the Acrobat application bundle
2. Right click the bundle and select "Show Package Contents"
3. Go to Contents - Plug-ins and remove "PitStop Pro.acroplugin", if it's present. If it's not there, go to step 4.
4. If you didn't find PitStop Pro in step 3, go to /Library/Application Support/Adobe/Acrobat/<version>/Plug-ins, and again delete "PitStop Pro.acroplugin". If it's not there, it should've been inside the Acrobat bundle (step 3).
5. Open a terminal and type (or copy-paste) pkgutil --forget com.enfocus.pkg.PitStopPro
6.
https://www.youtube.com/watch?v=6uXJlX50Lj8