Water hose No. 1 (coolant control valve side) removal note
WARNING: This page is about a different car, the 2020 Mazda CX-30. However, it is still accessible from the selected car via links, so may be relevant.
Move the retainer in the direction of the arrow shown in the illustration.
Courtesy of MAZDA MOTORS CORP.
Disconnect the quick release connector from the coolant control valve.