Supposedly you can PUSH on this plastic ring on the intake manifold and PULL out the brake line. I tried that 10,000,000 different ways and couldn't get it out.
The easiest way in my opinion is to use a razor knive and slit the line at the brake booster and the one-way valve. You can then remove the 6" piece of hard plastic line. You can replace it later with some 3/8" heater hose and a couple of spring clamps.
BTW, don't yank on that plastic piece that goes into the manifold. Of you get this...
HTH,
BP