I know some people like to keep the bass for themselves, and some head units have sub-woofer controls but you have to find the feature and disable then enable.. blah blah blah.. takes forever cycling through the menu.
A quick and simple way is to install a switch for $5 (purchased at home depot)
There really is no instructions, except to cut the remote wire from the back of the head unit and connect it to the switch, put the switch in a convenient location and voila.. this switch will cut the signal from the head unit to the amp and your amp will shut off, hence shutting off your bass but still keeping your door speakers playing.
Crappy picture from my camera phone, but you get the idea.