How to use Purchase Order integration instead of PayPal on the form?

I've created my form however the payment auto select paypal whereas i would like to opt for purchase order instead. How do i edit them?

If you would like to use Purchase Order integration instead of PayPal, you can delete PayPal field and then add Purchase Order. All products of payment field will be transferred to Purchase Order automatically. 

We will gladly assist if you need any further help.