How to unset the backdrop in the preferences?

[Andre Alves Garzia]

Hey Friends,

This will sound silly. I am on Windows 10 using LC 9.x, I've set a 
backdrop on preferences and now I want to unset it but I can't find a 
way to do it. There are only options to select a new color but no way to 
clear it. Can anyone help? Executing `set the backdrop to none` every 
time I boot LC is getting tiresome.

cheers

andre