Clicking on Close Tour when editing a tour removes it from your Current & Upcoming and Completed sections and moves it to the Closed Tours section of the Manage Tours page.
Once a tour is closed, it can not be edited in any way. It is important that you only mark a tour closed when you are sure you require no further changes or adjustments.
However, even though a tour has been closed and you are no longer able to make any edits, you can still access the tour data. Click on the tour from the Closed Tours area of the Manage Tours page.
You can also still access the tour data in Reports available to Tour Merch Mgmt package users and above.
For SoundScan Reporter users, you always have access to your historical sales data by viewing Closed Tours from the Manage Tours page. See: Can I see all of my music sales by year or by tour? (SoundScan Reporter).