Is the assembly removed from the door yet?
To remove the mirror(glass), you warm it up with a hairdryer. Then carefully work a narrow putty knife or butter knife in between the glass and plastic backer. Start at the inside lower corner. It helps to have the mirror adjusted so the corner is proud. Gently pry the glass and foam sticky tape away from the plastic backer. Once they are removed you should be able to see the fixing screws that hold the motor assembly into the housing via openings in the plastic mirror mount.
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