If you find you need to remove the VerticalResponse app from Salesforce, just follow these steps. Remember, uninstalling will remove ALL stats provided by VR, so all email responses will be removed from Leads and Contacts. This can only be done by a Salesforce admin though, so you may need to ask that person in your organinzation.
Go To Setup > App Setup > Installed Packages
Find VR for Appex and click on the linked name.
On the page that comes up click Uninstall and a list of everything being removed will come up. At the bottom of the page click the box to uninstall and the uninstall button. Salesforce will remove all the componants for the VR package. Again, this is permanent and all stats associated with email campaigns will be removed.