Yes, you can.

Free margin shown in your Personal Area is a ‘floating’ amount (constantly changing) of funds which can be withdrawn at any given moment. However it’s not encouraged to withdraw with open positions, as there is a possibility that your Free Margin drops enough to impact open positions, unintentionally closing them due to Stop Out.

We recommend further reading about how to calculate margins; then you’re better able to plan your withdrawals so they don’t unintentionally impact your Free Margin.