If you hold cash in your share trading account and it is being used to maintain open positions on your CFD account, you will not be able to withdraw these funds until this cash is no longer being utilised as collateral. To do this, you may be required to fund your CFD account, or your share trading account, or close some open positions on your CFD account, as necessary.
If you hold instruments in your share trading account that are being used to maintain open positions on your CFD account, you will be able to instruct the sale of those instruments, provided your collateral value does not fall below the amount of margin required to fund the open positions on your CFD account. This is because when instruments are sold, the resulting cash should have a collateral value greater than the collateral value of the stock, as there is no haircut on the value of cash held.