How to remove all listeners in an element

I have a button, and I added some eventlistners to it:

document.getElementById("btn").addEventListener("click", funcA, false);
document.getElementById("btn").addEventListener("click", funcB, false);
document.getElementById("btn").addEventListener("click", funcC, false);
document.getElementById("btn").addEventListener("blur" , funcD, false);
document.getElementById("btn").addEventListener("focus", funcE, false);
<button id="btn">button</button>

I can remove them by:

document.getElementById("btn").removeEventListener("click",funcA);

What if I want I want to remove all listeners at once, or I don't have the function reference (funcA)? Is there a way of doing that, or I have to remove them one by one?