Replacing the front and rear speakers on a Renault Megane 2
Front speakers
The front door speakers are covered by a plastic panel.

To detach the panel, pull the front part of the panel away.

There's an extended clip at the back of this panel, be careful not to break it.

Remove the speaker mounting screws.
Disconnect the connector.
Reinstall in reverse order.
Rear Speakers
Remove the rear door trim.
When removing the rear door trim, keep in mind that in addition to the clips, it is sealed with a special adhesive.

Fig. Removing the rear speaker: 1 - Mounting screws
Remove the speaker mounting screws and remove it (Fig. 4).
Disconnect the speaker connector.
Installation is the reverse of removal.
Gently tighten the speaker mounting screws.