Follow the hose from the master cylinder (up at the footbox) down to the connection. This hose is covered with a heat protection cloth. There are two ends for the "quick disconnect" pair and on the pedal side the fitting has a white plastic ring around it. You need to push the quick disconnect pair together and then also push the white plastic ring, which unlocks the quick disconnect. I can only look at the used master cylinder I have, so I may be forgetting that the white plastic ring is covered by a black plastic cover. I have disconnected this a few times, never with the tool. I think I only used a small screwdriver to poke the white ring into the unlock position. It is not spring loaded, so if you push, it will stay. Good luck.
