Scenario
There are instances that a custom item field is locked or will not allow users to update its current setup.
Solution
To remove the lock in Custom Item Field, make sure to delete all the association of this field in the Web Site Setup page under Commerce > Websites > Website List then edit the website.
- In the Search Index tab, make sure that the custom item field is not used inside the Search Fields, Facet Fields and Sort Fields
- In the Field Sets tab, make sure that the custom item field is not used or added in the Fields Included in Field Set column