Quick Connect Fittings (Plastic Collar): Removal
WARNING: This page is about a different car, the 2002 GMC Sierra, 2002 GMC Cab & Chassis Sierra, 2002 Chevrolet Silverado, and 2002 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
Disconnect the negative battery cable. Remove fuel filler cap. Using compressed air, blow any dirt out of the quick-connect fitting. Squeeze the plastic retainer release tabs. Pull the connection apart.