The Archive Trip function lets you remove your trip from your Open Trip List without deleting trip information in the event you wish to return to it in the future. Some people use this option (along with 'Tentative Trip', which works the same way) to reduce the number of open trips they have to avoid confusion.
To Archive a trip, click on the Wrench Icon and select the Trip Settings option.
This is the wrench icon:
Trip Settings will open in the drawer and your map will gray out (on desktop) to indicate you cannot interact with it while your Trip Settings are open. To archive your trip select Archive from the drop down menu in the middle of the drawer and click Save.
Archived Trips can always be returned to your Open Trip menu at any time. To view an archived trip (or to return it to 'Active' status) start by clicking Open Trips in the header.
The Open Trips window will appear. To locate the archived trip you're looking for, select the Archived Trip tab from the Open Trips window. Then click Open.
You'll notice your trip has '(Archived)' written next to the trip name.
To return it to Active Status, click on the Wrench Icon once again followed by the Trip Settings option. Repeat the process as the same you would when you first archived your trip, only this time select 'Active' instead.
To complete, click Save. The trip will return to your list of Open Trips.