You might have not found that option because you might have customers that have the Contact Type set to Both. This option is now not available in Zoho Books and hence this option has been disabled.
To have this option enabled for your organization, please follow the instructions given below:
Once you complete these steps, please send us a feedback. We will make the necessary changes from our end for you to view the option for the custom role.
Online accounting software
for small businesses.