You can remove a payment method after 60 days have passed since your first deposit using that payment method.
Just log into your account and tap the deposit button in the top right corner. Once you are on the Deposits page, you should see a trash can icon. Click the icon to remove a payment method. If the trash can icon isn't there, that means you still need to wait for your 60 day waiting period to end.
You may only request to remove a payment method once (1) in any calendar month, and no more than five (5) times across any twelve-month span. For security reasons, PayPal does not permit you to remove your account.