Browse to Google Groups for uni.edu to see a list of the groups you a member of. If you are logged into your UNI Gmail account , you can click on the "Groups" link at the top.
If the URL in the address bar does not end with uni.edu, you are at Google's public group directory which is not maintained by UNI. Click on http://groups.google.com/a/uni.edu  to be sure you are at UNI's Google Groups page.
Complete instructions on removing yourself from a Google Group can be found here: