Except For STI Model

Lift up the vehicle, and then remove the front wheels.
Remove the union bolt and the caliper bolt, and remove the caliper body assembly.
CAUTION:
- Do not allow brake fluid to come in contact with the painted surface of the vehicle body. If it does, wash off with water and wipe away completely.
- Prepare a container to catch grease or oil, etc. If any grease or oil spills, wipe it off and clean immediately to prevent from penetrating into floor or flowing outside.
Fig 1: Locating Union Bolt And Caliper Bolt Of Caliper Body Assembly
Courtesy of SUBARU OF AMERICA, INC.
Remove the support - front disc brake.
1. Remove the pad - disc brake front.
  
  Fig 2: Removing Pad - Disc Brake Front
  Courtesy of SUBARU OF AMERICA, INC.
2. Remove the mounting bolts, and then remove the support - front disc brake.
  
  Fig 3: Locating Mounting Bolts Of Support - Front Disc Brake
  Courtesy of SUBARU OF AMERICA, INC.