Enable reorders in Magento 2 helps customer to reorder after they complete their purchase. Customer can make reorders immediately from their account or ask admin to reorder in the backend. If you don’t want to allow customer reorders, you should consider that feature because reorder feature is enabled by default.
Stores. In the
Salesin the panel on the left
Reordersection, and continue with following:
Allow Reorder field, select
Yes to allow reorder
When complete, click
Ref: Magento 2 User Guide
It comes to the end of tutorial: How to enable or disable reorders in Magento 2.