How can I remove Credit Card & Billing Details from a form?

I just need to collect orders from customer by providing them with a Order Portal, therefor there is no need for billing details & credit details.

You are using Authorize.net as a payment field in your form, which is why you have the credit card fields there. 

If you do not want to collect actual payments and just want to use the feature to setup products, then you can remove the current payment field you are using and add "Purchase Order" field under the "Payments" list. Here's how:

1. First, select the payment field in your form and click the "Remove" button. 

2. After that, navigate to your "Payments" tab, find the "Purchase Order" field and drag it to your form. That should automatically re-add the the previous products that you set up. 

3. Save the changes and test your form.

Let us know if that works.