Question:

Is a user able to filter on Inactive Document Types, Subtypes, or Classifications when searching in Vault?

Answer:

A user can filter on Inactive Document Types, Subtypes, or Classifications when searching in Vault.  If the affected Document Type, Subtype, or Classification is deleted from Vault, users are no longer able to filter on these when searching in Vault.  

Related Documentation:

Vault Search Documentation: Filtering on Document Type