The actions within the Inventory and Requests modules differ slightly.
When a member leaves, a copy of their stuff remains in the Inventory.
The name of the original Owner of all items will remain available in the item details. Follow this process if you'd like to manually change the Owner of those items in bulk: Edit inventory item details via Excel
When a member leaves, all their past requests will remain in the Lab.
The member's name will still be associated with the old requests in order for the Lab to keep a proper record.