You can move money out of your Collective in several ways:
submit expenses to withdraw funds
donating to another Collective in the same fiscal host
giving the remaining balance to your host by clicking the 'Empty Balance' button
Due to the design of the Open Collective system, sometimes if you try to withdraw 100% of your balance, a small amount will be unintentionally left behind. This is usually caused by fees being hard to predict exactly.
If this happens, go to 'edit Collective > 'advanced' and use the 'Empty Balance' button to transfer the remaining funds to your fiscal host.