I am using version v9.1.0-1.0.8. I open the configuration of the addon, go to Displays > Primary > Border, and uncheck enable. This does not seem to do anything. To verify I also tried changing the border color to something like red. When selecting this color and going back in, it just goes back to the default color.

The goal is that I also use Masque and would like to get rid of the borders. Notice in the screenshot the borders showing?

Load Hekili by itself and see if the border is removed. It looks to me like you have multiple addons skinning it.

Yes that did the trick. Thank you for the prompt reply.