GMC 2007 Envoy Denali Owner's Manual page 438

Backglass Wiper Blade Replacement
1. Lift the wiper blade assembly up and out of
the park rest position.
2. Pull the wiper blade assembly away from the
backglass. The backglass wiper blade will not
lock in a vertical position, so care should
be used when pulling it away from the vehicle.
3. Rotate the wiper blade assembly, and pull it
off of the wiper arm. Hold the wiper arm in
position and push the blade away from
the wiper arm.
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4. Replace the wiper blade.
5. Return the wiper blade assembly to the park
rest position.