This article explains if it possible to change or remove the 'Powered by Jive' logo shown in the Jive for Outlook plugin?
Jive Interactive Intranet - Extended features, add-ons & plugins
Unfortunately, the 'Powered by Jive' logo cannot be removed or changed using the standard out-of-the-box options in the Jive for Outlook plugin.
Any further customization needs engagement with Aurea Professional Services. Please contact your Account Manager to learn more about additional customization possibilities.