One of the most asked questions I get from End Users about SharePoint is “How do I remove the connection from Outlook?” This is usually requested because they are receiving an excessive number of authentication prompts in Outlook due to not having their machine configured correctly or some other bug. In most cases, the prompting should end once they add the site to the Trusted Sites, allow IE to pass authentication, and setup the WebClient in the registry. Note: At my organization, we also have an installer that will do all of that for you. If that is too much and they just have to have it removed, here are the steps.
1. In Outlook, go to Tools and Account Settings
2. Click on SharePoint Lists
3. You could see multiple lists here if you have made more than one connection. Highlight one and then click Change.
4. If you have accessed SharePoint on multiple computers, it is possible that the others have a connection as well. To clear that up, you need to check the box “Don’t display this list on other computers I use.” If you don’t do that, it is possible the list will come back. Click OK and return to the List. You can repeat this process on any other lists you wish to remove.
5. Once you have checked that box for each list, click on Remove and then OK.
That’s all there is to it. One thing you can do in the future if you don’t want the list to show up on every instance of Outlook you touch is click that checkbox before you add the list.
You’ll find it under Advanced when you try to add the list