WARNING: This page is about a different car, the 2015 GMC Acadia, 2015 Chevrolet Traverse, and 2015 Buick Enclave. However, it is still accessible from the selected car via links, so may be relevant.
Disconnect the electrical connectors at each end of the antenna.
If the antenna cable is taped into the wiring harness then cut the ends off the old antenna and route the new antenna as close to the old one as possible using tie straps to secure the new cable.