If you wish to remove/disconnect your PayPal account from your Challengermode account, you can do so in your PayPal account under your "pre-approved payments".
To view or change your pre-approved payments, 1) login to your PayPal account, 2) Navigate to the Payments tab:
3) and click on "Manage pre-approved payments". This will take you to a list of all the shops, site or merchants you have a billing agreements with. Look for the one that says "Challengermode AB".
Please note that you can only have one PayPal account connected to your Challengermode account for security reasons. It's not possible to change accounts.
So if you remove an account you will only be able to add the same PayPal account again by default.