You cannot turn off the withdrawal confirmation emails you receive from Prime Trust. This is a security feature we have to protect our users and prevent anyone other than you from ever moving your Bitcoin. You have legal ownership of the bitcoin with a licensed and regulated custodian (Prime Trust), so they require you as the legal owner to authorize all disbursements, including every recurring withdrawal.
If you are frustrated by needing to confirm withdrawals often you can set a high threshold for your auto-withdrawals to reduce their frequency. To set your threshold higher, click the "every 0.01 BTC" button (example below) to slide the threshold to your desired amount.
For more information on how withdrawals work read here.