Yes, but it will involve a lot of manual intervention. Firstly to be offloaded from the flight & then secondly to be escorted from airside back to landside. These steps may both involve some waiting around. If you have checked luggage then this will also have to be pulled causing potential delays to the flight.

You should be able to then request a refund if allowed by the fare rules applicable to your ticket but it will probably require a phone call & up to 6 weeks to have money back in your account.

I would point out that you only need to pass through security 35 minutes before departure so at what point are you actually going to decide not to travel?