Yes, you can take funds out of your Bidvest Bank Investment account at any time.
Due to the integration between your Bidvest Bank account and your Bidvest Bank Investment Account, the process of moving "Withdrawable Funds" (funds that have settled) from your Investment account to your bank account should be almost immediate.
For full details on "Withdrawable Funds" and how to withdraw them, please visit this FAQ article How do I withdraw funds from my Investment account?