Electrical System: Replacement

WARNING: This page is about a different car, the 2017 Mazda 3. However, it is still accessible from the selected car via links, so may be relevant.

Use the appropriate tools to remove a terminal as shown. When installing a terminal, be sure to insert it until it locks securely.
Insert a thin piece of metal from the terminal side of the connector and with the terminal locking tab pressed down, pull the terminal out from the connector.

Fig 1: Removing Terminal From Connector

Courtesy of MAZDA MOTORS CORP.