Push release

Disconnect the negative battery cable.
Disconnect the vapor tube from the fitting.
1. Press the retainer clip in.
2. Disconnect the vapor tube from the fitting.
  
  Fig 1: Disconnecting Vapor Tube From Fitting
  Courtesy of MAZDA MOTORS CORP.
Inspect the fitting and the tube for damage.
Remove any dirt or obstructions.
Push the tube into the fitting until it snaps in place.

Fig 2: Pushing Tube Into Fitting
Courtesy of MAZDA MOTORS CORP.
Pull on the connection to make sure the fitting is secure.

Fig 3: Pulling Connection For Checking Proper Engagement

Courtesy of MAZDA MOTORS CORP.