Hello Tien Duy Nguyen,

You can cancel sale order by this app, Even after Sale order was done , Cancel Sale Order App link.
 https://apps.odoo.com/apps/modules/11.0/cancel_sale_order/ 

Thanks

Hello Tien Duy Nguyen,

There is one module in odoo store which helps you to cancel order / Reset to draft in just one click.

Cancel Sales Order In Odoo

Here is the some highlights of this app.

• Cancel Delivery Orders attached with Sales Order, even if those are processed.
• While cancel delivery order, it will affect stock & remove journal entries (If any) created for stock valuation.
• Cancel Invoices which are created from the sales order.
• If payment is made for an invoice, it will unreconciled a payment from the invoice & cancel it.