How to make the Reporting Establishment Field as non-mandatory

Summary:

Hello,

I want to make the "reporting establishment" field in person Management not mandatory.

Step to navigate to the page :

My client-> Person Management-> Search for a person number -> Click on the person number -> edit -> correct -> click on review

When clicking on review, am getting the below error. Hence i want to make the field non mandatory.

Content (please ensure you mask any confidential information):

I am having an issue whereby the field reporting establishment is mandatory.

I have create a sandbox with page composer, and in structure tab, i have untick the "required" field.