Transferring funds between accounts is simple and there is NO charge to it.
You will need to contact Customer Support, include both account numbers (clearly stating from which to which account) and the amount that you wish to transfer in the request. Both accounts must belong to you and be under your name.
Please make sure to confirm the available equity you have in your account, you may need to close your positions until the request is completion.
Please note: Transfers may take up to 1 Business day.