You can certainly do this! You would need to go to audience > active > actions > archive all.
If you were to import any contacts that were previously archived they will still pull back in assuming you want these active!
Furthermore, because archiving can be confusing when comparing to deleting, archiving will remove the contact from your account for all intents and purposes. Archived contacts will not count towards billing for subsequent months nor be in your regular account interface when you are sending.
For a bit more on this feel free to take a look at our resource center article here: