A document type is used to classify project documents.
If you are a Vista user, your Document Types are automatically imported from your ERP and can not be added, edited, or deleted in Team.
If you are a Spectrum user or have a standalone installation, Team comes with stock Document Types. You can add, edit, deactivate or delete Document Types in Team as needed.
You can deactivate a document type in Team. Inactive document types do not appear in lookups and are not available for use.