A property may be archived because it's no longer needed but if you need to unarchive it at any time, it's easy to do.
1.
Firstly, click the "filter" icon in the top left corner, just above your list of properties.
2.
Tick the Show archived checkbox as illustrated below, then then green Filter button.
3.
Your client presentation list will now populate with both current and archived properties. You can distinguish archived properties by their unique "folder" icon just to the left of the property address.
4.
Finally, to unarchive the desired property, click on the folder symbol which will bring up the following dialogue box. Click the green Yes button to restore the presentation.
5.
Voilà! The presentation has now been restored, and you can use it as normal.
EXTRA.
If you wish to hide the archived properties again, simply repeat Steps 1 - 3.