The following tutorial covers changing diazo Uni Theme footer on a Plone 4.1 website.
Uni theme footer is subdivided into two parts: footer with Plone info (1) and theme credits (2) with standart Plone colophon.
To edit footer, access Zope Management Interface, and open portal_view_customizations, and plone.footer among long list of available items. Press Customize to enable current footer editing and edit footer text. Do not forget to save changes when you finish.
To hide theme credits (2) and Plone colophon you will need to add a special class to your ploneCustom.css.
#portal-colophon {
display: none;
}
Read our tutorial on how to customize CSS stylesheets in Plone.