After setting up a site mailbox, you may decide that you don’t really need it. You can remove the Site Mailbox app, which essentially hides the mailbox from those who are using the site.
Important: The site mailbox feature in SharePoint Online is being deprecated beginning in March, 2017. This feature will be removed entirely in a future release. New SharePoint Online organizations no longer have access to the site mailbox feature. Existing SharePoint Online organizations can no longer create new site mailboxes. Any site mailbox that was set up and deployed before March, 2017 will continue to function.
We will provide a process to help transition your existing site mailbox sites to an Office 365 Group in September, 2017. If you currently use the site mailbox feature in SharePoint Online, you should consider changing to Office 365 Groups instead to support your email collaborative scenarios. For more information, see Use Office 365 Groups instead of Site Mailboxes.
Note: The site mailbox feature is still available in SharePoint Server 2016, SharePoint 2013 and SharePoint 2010 products.
Click Settings > Site contents.
Under Lists, Libraries, and other Apps, point to Site Mailbox, and then click ... for more information.
Click Remove on the box that pops up.
Click OK to remove the site mailbox app.
Note: If you remove a mailbox from a site, it won’t be displayed on the site, but it will still be visible in Outlook (if you’re using Exchange).
What else do I need to know?
There are a couple of things worth noting about removing a site mailbox:
The only way to fully delete a site mailbox is to delete the entire site itself. When a site is closed or deleted (either manually, or by following site closure policies), the site mailbox is also closed or deleted.
After removing the site mailbox app from a site, mail sent to the mailbox will still be stored. If you add the mailbox back to the site later, any mail sent to the site mailbox since it was originally created will still be there.