Chevrolet 2006 Avalanche Owner's Manual page 140

3. Pull each cargo panel up and then out from the
side rails and set it aside. Remove as many
cargo panels as needed.
2-66
4. If cargo panel 1 needs to be removed. There are
latches on both sides that need to be released.
After you have removed each cargo panel, store them
within the cargo storage area using the cargo panel
storage system.