How to remove metal ring from copper pipe?

Hey everyone, I’m trying to replace our shut off valve under the sink but I’m struggling with that tiny ring that is stopping the screw to come off. Any ideas how to remove it? I’m on YouTube for hours but couldn’t find anyone explaining this.

Thank you in advance!

Hey everyone, I’m trying to replace our shut off valve under the sink but I’m struggling with that tiny ring that is stopping the screw to come off. Any ideas how to remove it? I’m on YouTube for hours but couldn’t find anyone explaining this.

Thank you in advance!