Unable to add PayPal to form

I have been unable to add PayPal to my form. Currently, I am using the free form to see how it goes. I tried to add the PayPal button, but it says I already have a payment method, but I don't see it. Can you assist me please? Thanks

Please note that you can only add one item coming from the "Payment Fields". 

In your case, you already have added the "Purchase Order" payment field. Here it is:

When you open the wizard, you can see that it is the payment wizard:

The "Purchase Order" payment field is usually used if you want to have the same functionality of adding products and setting up an order field but you do not wish to have a 3rd party payment integration on it.

To learn more about setting up order forms, you can check these guides: 

https://www.jotform.com/help/47-Order-Form-Basics 

https://www.jotform.com/help/49-Order-Form-Types 

https://www.jotform.com/help/165-Setting-Up-Your-First-Order-Form 

Noticed that payment integrations and Purchase Order field has the same wizard. 

I hope that helps.

Do I have to redo my entire form?

It will not require redoing the form.  When you delete the purchase order field, there will be a pop-up asking if you would like to save the products in your payment field.  Click on "Yes" and the products will be added to the PayPal field when added to your form.