Defeat Wither in bedrock edition?

Play minecraft on Windows 10 Edition and I wanted to ask if anyone knows a method to defeat the wither without being too hidden

He always gets out under the portal and under det nether ceiling

Watch a tutorial

I already got it from LarsLP but it doesn't work

Probably wrong version in 1.16

And yes, I did it in the West too, but it still didn't work

Sure you did everything right

Try it a while in creative mode until it works

The best thing to do is watch the video from BastiGHG he does it more often and therefore in many versions and different ways.