Remove, unpin or delete Adobe Acrobat icon from the Start Menu, the desktop and (if you have it there) from the taskbar.
Go to C: > ProgramData > Microsoft > Windows > Start Menu > Programs and you'll find the "sinner" "Adobe Acrobat XI Pro" with the wrong icon. The that looks like a shortcut. Delete it!.. Close the window.
Go to C: > Program Files (x86) > Adobe > Acrobat 11.0 > Acrobat... and find Acrobat.exe
Right click on Acrobat.exe > Send to > Desktop
Right click again on Acrobat.exe > Pin to Start Menu... and close the window
Right click on Acrobat.exe - shortcut (that you just created on your desktop) > Copy
Go back to: C: > ProgramData > Microsoft > Windows > Start Menu > Programs... and Paste the shortcut here (you need administrator privileges for that)
Rename this shortcut from "Acrobat.exe - shortcut" to "Adobe Acrobat XI Pro"
Close the window
Now if you open any PDF document, the right icon will appear on the taskbar.