I have selected a template that has a purchase order pay option. How do I change to my paypal?

When I go under payments it says that I am only able to have 1 way to pay… I only want my players to be able to pay with paypal. 

Yes, it is not allowed to add more than one payment integration to a form, to delete the current one you need to click on the payment section to get its options, once there click on the delete icon.

Here's also a guide that will help you to integrate your form with PayPal: https://www.jotform.com/help/391-How-to-Integrate-Form-with-Paypal 

If you have any question, let us know.