I would like to disable Sandbox but clicking the link does nothing

I would like to setup PayPal to process payments from my form. But, when I click the link to disable Sandbox Mode, nothing happens.

That is because you have not connected your Square account first. You should go to the settings, select Live, and click Connect with  Square button:

I am trying to associate Paypal not square how do i do that
...

I see. In my screenshot, you'll see the red Trash bin icon. Click that to delete Square payment, and add Paypal from the list of Payment options. Don't worry about the product items, they are saved and will be automatically added by the form builder.