Horn LO

Disconnect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION .)
Remove the front bumper. (See FRONT BUMPER REMOVAL .) (See FRONT BUMPER INSTALLATION .)
Disconnect the connector.

Fig 1: Horn Low, Connector And Bolts With Torque Specification
Courtesy of MAZDA MOTORS CORP.
Remove the bolt.
Remove the horn LO.
Install in the reverse order of removal.