Attio uses two separate but related concepts: archiving and deleting.
Deleting should be considered permanent. Any data you delete will eventually be removed from our servers entirely, without the ability for restoration. As such, deletes should be handled extremely carefully.
Deleting occurs over the API using the conventional REST semantics of the DELETE HTTP verb.
Archiving is softer, allowing data to remain in the system, albeit in a more hidden state. The exact behaviour of archived data will depend on the object you are archiving but the behaviour will be documented for the given endpoint.
Data is archived over the API by setting the is_archived property to true and restored by setting it to false.