Ever tried to disable quick create completly? You will notice that this isnt able for all entities ;) It will stay for some activities and thus the QUICK Create + in the Ribbon will be visible the whole time.
Playing around with IE Developer Tools it shows that the section is called GQC (Global Quick Create).
To hide this section simply go to your CRM Frontend server and navigate to
C:\Program Files\Microsoft Dynamics CRM\CRMWeb\_controls\navbar and create a Copy / backup file of the navbar.css