Chevrolet 2005 Tahoe Owner's Manual page 311

The following steps must be performed on each of the
push-pins to remove the air dam:
1. Insert a tool into the
push-pin slot and pull
downward until the
push-pin snaps loose.
2. While continuing to
pull downward on the
push-pin, squeeze
and turn the
expandable end of the
push-pin with a tool
until it releases
from the retainer.
When you are back on roads, though, be sure to
replace the air dam.
Notice: Operating your vehicle for extended
periods without the front bumper lower air dam
installed can cause improper air flow to the engine
and may allow things like fog lamps or tow hooks
on the front of your vehicle to be damaged. Always
be sure to replace the front bumper air dam when
you are finished off-road driving.
3. Pull the push-pins
and lower air dam
assembly away from
the retainers until
the lower air dam
is free.
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