Following a PC crash I have reinstalled Acrobat XI. I need to deactivate my version on previous installs. Serial number is [removed-kglad]

these are public forums.  disseminating your serial number is likely to get it black-listed.

if you see an activation count error, contact adobe support during pst business hours by clicking here and, when available, click 'still need help', https://helpx.adobe.com/contact.html and request an activation count reset.