Can't remove BETA RTX from my bedrock Minecraft

Hi, 
I wanted to discover the RTX for Minecraft so I submitted to the beta.

Now I want to play with my friends and I tried everything including the "Powershell command" to make my bedrock Minecraft up to 1.14.
I figured out that some others players are experimenting the same problem as mine.

I would like to know what can I do ?

Thx.