Ok, so you used to be able o rob the bank right when the bank system came out. However, whenever someone robbed the bank the server would crash. This made it super laggy, so the owners had to disable robbing the bank. When the bank was robbed and the player had no insurance it took money from their bank account. It is not currently possible to rob the bank, but you can go through the door and into the tunnels and get to where you used to be able to rob it. Maybe in the future the bank will be robbable again once the plugin is fixed.