If you're talking about where the caliper hardline connects to the flexible rubber (or stainless) line, make sure to remove the bracket that holds it in place first. Counterhold the hardline fitting with a flarenut wrench and use another flarenut wrench on the flexible side as well.
The same thing works further upline when you remove the rubber/stainless from the hardline going to the master cylinder.
Whatever you do, protect that hardline going to the m/c
at all costs. You really, really don't want to replumb your car's brake lines.
