Need help writing custom code for a button in ZOHO CRM. Looking for a email opt out button.

Need help writing custom code for a button in ZOHO CRM. Looking for a email opt out button.

I need assistance with creating a button in which I can select a contact and have it opt out of email automations/campaigns. The email opt out field is a boolean. If someone could help me write the code for the contacts module, that would be greatly appreciated!