[PayPal Express] Hide Shipping Methods and Shipping Costs

How can I hide the Shipping Methods when redirecting a user to PayPal Express?
Those are the parameters I send to PayPal (via the oepaypal module):

  string(4) "84.0"
  string(5) "de_DE"
  string(4) "Mark"
  string(8) "Foo"
  string(0) ""
  string(168) "..."
  string(111) "..."
  string(4) "Sale"
  string(158) "..."
  string(1) "2"
  string(4) "1.19"
  string(3) "EUR"
  string(4) "1.25"
  string(50) "..."
  string(50) "..."
  string(5) "32.25"
  string(12) "Gesamtsumme:"
  string(4) "1.25"

This results in an error from PayPal: “Flat-rate shipping options are missing; you must specify flat-rate shipping options when you specify a callback URL.”

If I pass 0 as shipping costs, the shipping costs are shown as “0.00” - but I want to hide them entirely.

How’s that possible?

Check PayPal api documentation if there is an option for hiding shipping costs, then if there is one, you can search for it in source code and set the value you want.