Remove Diesel Tank Stop Idiots Protection

Hello guys, does someone know if, or how to remove the tank protection from petrol taps in the diesel tank socket of the Seat-Leon? It was originally intended, so that an average American can’t accidentally refuel petrol in the diesel vehicle. At the moment, it is causing me problems if I want to refuel from my 20 liter canisters. There are adapters, but 9 EUR for such a plastic part is completely exaggerated.