Using Windshield Glass Knife

Disconnect the ground cable from battery. (Models with wiper deicer)
Remove the trim panel - front pillar UPR. < Ref. to REMOVAL , Upper Inner Trim. >
Remove the cowl panel assembly. < Ref. to REMOVAL , Cowl Panel. >
Disconnect the wiper deicer connector. (Models with wiper deicer)
Remove the stereo camera cover and stereo camera. (Models with EyeSight) < Ref. to REMOVAL , Stereo Camera. >
Remove the molding - front window from the glass - front window, and attach protective tape on the body side of the circumference of the glass - front window.

Fig 1: Identifying Molding, Body Panel, Adhesive, Glass And Protective Tape
Courtesy of SUBARU OF AMERICA, INC.
Remove the glass - front window.
1. Apply sufficient amount of soapy water to the adhesive part and insert the windshield glass knife.
2. While holding the edges of the knife and the glass - front window at a right angle, move the windshield glass knife parallel to the edge of the glass - front window, and cut the adhesive along the surface and the edge of the glass - front window.
  CAUTION:
  - Cutting of adhesive part should be started from an area with wider gap between the glass - front window and the body.
  - Never twist the windshield glass knife.
  Fig 2: Removing Front Window Glass
  Courtesy of SUBARU OF AMERICA, INC.
3. Disconnect the locating pin - front window, and remove the glass - front window.
  NOTE: The locating pin - front window are bonded to the corners of the glass - front window. Use piano wire to disconnect the pins.
  
  Fig 3: Identifying Front Window Pin, Body Panel And Front Window Glass
  Courtesy of SUBARU OF AMERICA, INC.