I am thinking of several options "do as you will", "do whatever you want", "do as you please", but I want to find a very original way to say it, maybe a slang, maybe a formal way to say it, but a way to say it that non-native people would rarely say.
There is the old Burger King slogan. Burger King is a U.S. based fast food restaurant chain. A well known advertising slogan for them is: "Have it your way." Burger King used this to say that they were flexible in customizing menu options to customer desires.
Here is the result of a search for this slogan.
Let's say someone is really giving you a hard time and they won't take no for an answer. Finally, you decide to let them do what they want. "Have it your way." That's one way it can be used. To be honest, I don't know how commonly used this would be by non-native speakers.
You could also say, "Do it your way."