If you are using a Volume License (common in corporate environments), there is no deactivation button. You simply uninstall the software to free up the seat.
You click "Help" > "Deactivate..." expecting to free up your serial number, only to find the option lifeless and unclickable. Here is why that happens and, more importantly, how to bypass it. adobe acrobat xi pro deactivate greyed out
The button may be greyed out simply because the software is not currently in an "activated" state on that machine. If you are using a Volume License (common
If the button remains greyed out and you are blocked from installing on a new computer: Adobe Acrobat Professional (De-Activate option greyed out) adobe acrobat xi pro deactivate greyed out