Spaces and channels cannot be archived, only content, but you would need to go to each content you'd like to archive. Do note that archiving does not deleted the content from your digital workplace, this just helps regulate your search.
This will hide it from your members, as well as it not being searchable to them. Admins will have access to see this space in the site manager.
Considering that this is not a functionality of igloo, If you would like to see this as a future feature on Igloo, please submit your idea to our Product Zone page here. Once you have registered, you will not only have the ability to submit your ideas, but you will also receive a notification any time the status of the idea gets updated by our Product Team. In addition, you will be able to view ideas that other Igloo users have submitted and up-vote submissions that you are also interested in seeing on the platform.
Please let me know if you have any further questions I can assist with.