There is a choice involved, in that you can opt for Freeview or one of the Freesat packages whereby you pay once and for all for the viewing equipment and get the BBC channels and whatever else is bundled in as free-to-air or free-to-view. Additional subscriptions you choose to pay for (or not) fund services which receive nothing from the licence fee and can't raise enough from advertising alone.
If you're saying that there should be a choice to opt out of the BBC, there are two problems: proving that you're not watching/listening/going online to access the services anyway (I bet you would be!), and an creating an enormous deficit in the finances of arguably the finest broadcaster in the world.
We can't pick and choose when it comes to funding public service broadcasting any more than we can select whether or not to pay for medical treatment for smokers, educating other people's children, or fighting wars we don't agree with.
We could scrap the licence fee and let the BBC sink or swim as a commercial broadcaster, but that could only lead to higher TV and radio subscription charges, coupled with a huge reduction in quality.