Delete order status
Go to the Settings menu, use Store Configuration >>> Order Statuses link to open 'Order Statuses' page. Locate the status you wish to delete and click on at the end of its row. Confirm you wish to delete this order status in a pop-up window.
Only custom order statuses can be deleted. Predefined statuses can be deactivated by clicking the button but cannot be deleted. Inactive order statuses show in the 'Active' column.