You change it on your phone and turn off media in the Bluetooth settings for that device. You can then set a routine to turn it on or a widget button via Nova launcher with a lot more effort.
Turning it off when you pull up to the shop driveway and then turning it back on when you leave is the simplest option, but takes a bit more effort. Unless you are in a revolving door at a shop then you'd only be doing this occasionally.