Judith Guthoerl demonstrates how.
First she loosens the nuts holding the flat front wheel on.
You can actually fix a flat without removing the wheel, but it usually isn't easier that way.
Step 1: Disconnect the Brake Cable
The wheel hangs up on the brake pads.
The brake calipers are too close together to get the wheel out.
She pulls the end of the brake cable out of the opposing bracket thingy so the calipers can pop apart, letting the wheel out.
Every type of brakes has a different way of doing this.