What happens to an archived goal?
The goal becomes inactive and can no longer derail, and goes into your archived gallery. You can still access the goal and data from the archived gallery or at the same URL as before. Some of the settings are frozen, but you can rename the goal, change its description, change the privacy, etc, and other similar tweaks.
If you want to restart the goal later to get back on the hook, you can do that with the Restart button on the right-hand side of the goal page. (If you don't see the Restart/Delete buttons on the right of the graph as in the screenshot, make sure you're logged in to the website!) You'll get some options to set your new rate and tweak your goal settings before the goal goes live again.
Keywords: inactive goals, what archiving entails, deleting goals