You can change the  'Add/Edit 3rd Party Agency' visibility between center and company level setup using the 'Module Configuration' option present in the Company Dashboard.

Access Path : Company Dashboard > Functions > Module Configuration > Agency Setup 

By default, the 'Add/Edit 3rd Party Agency' option is available on the center level setup. You can change the position of the option by selecting the 'Company Level' radio option on the 'Agency Setup'.

Center Level Setup - 
Add/Edit 3rd Party Agency 

Access Path : Center Dashboard > Setup > Other > Add/Edit 3rd Party Agency

Company Level Setup - 
Add/Edit 3rd Party Agency

Access Path : Company Dashboard > Setup > Agency  > Add/Edit 3rd Party Agency