Answer
No single built-in 'deactivate site' action exists — winding down a site in practice takes a combination of measures, roughly graduated by how strict the restriction needs to be. A 'soft' approach: inactivate Supplier-for-Purchase-Parts and Sales Parts records for that site (blocking most new supply/demand transactions) and lock its inventory locations — reversible, and full visibility remains for anyone who already has access. A stricter approach: set the site's Inventory Parts to 'Do Not Sell' status, which blocks new supply (PO/Shop Order) and demand (CO) transactions more thoroughly while preserving visibility for reporting/history (note this doesn't block a plain inventory move between sites). The strictest approach: remove site access from users' permission sets entirely, making the site fully invisible to them — the strongest protection, but it also removes all visibility including historical data, and there's no partial/read-only-by-site capability in general (if a user can perform a given transaction type at all, they can perform it in any site they have access to). A practical sequence that's worked in real deployments: first prevent users with receiving/warehouse access elsewhere from also having access to the retiring site, send a company-wide notice that transactions in the retiring site codes are no longer allowed, apply the soft-line measures, and only escalate to the stricter options if needed over time.