You have to remove the entire door panel. There are a few screws (phillips) that need to be removed as well as the push pins on the outer perimeter of the panel. Once the panel is separated from the door, you will need to disconnect the door handle by removing the rod that is attached. Disconnect the wiring harness for your windows/locks and disconnect the wire on the back of the courtesy light at the base of the panel. After that, you will see the four screws that hold the actual 6x9 speaker in place. Remove those and disconnect the wiring.
A few other thoughts...some reference charts will tell you that you can get a 5" deep 6x9 for the door but they don't clarify. If you buy an aftermarket speaker, the magnet diameter is significantly larger and interferes with the vertical beam inside the door. Just keep that in mind in your speaker shopping and don't buy the high powered 6x9 unless you're prepared to do a custom installation. My recommendation would be to get an original Boston that you know will fit it (and the wiring is already there) and be done with it.
3.5 in the top dash for Chrysler 300
The 2006 Chrysler 300 has a V6 engine.
The 2006 Chrysler 300 has 24 valves.
The 2006 Chrysler 300 has a 4-speed automatic.
A 2006 Chrysler 300 was not built with two batteries.
The 2006 Chrysler 300 is a gas-powered vehicle.
The curb weight of the 2006 Chrysler 300 is 3712 lbs..
The 2006 Chrysler 300 runs on regular unleaded.
The 2006 Chrysler 300 has double overhead cam (DOHC).
The 2006 Chrysler 300 has a drag coefficient of 0.33 Cd.
The 2006 Chrysler 300 is 16 ft. 4.8 in. (196.8 in.) long.
The height of the 2006 Chrysler 300 is 4 ft. 10.4 in. (58.4 in.).