To withdraw your tap the hamburger icon.
Tap "Accounts dashboard".
Find account from which you want to withdraw your funds and tap "Account overview" button.
Click on the "Withdrawal" button.
Type amount to withdraw, your 2FA Code, and click "Confirm".
Swipe down and click downside arrow to choose already confirmed address from drop-down menu list.
If you are performing withdrawal for the first time, enter your new wallet address by tapping "+" icon. 
Type your wallet address and tap "Confirm withdrawal".
You will see a notification that for safety reasons PrimeBit sent you an email to confirm your new wallet address.
Go to your mailbox and open email "Please verify your withdrawal address". If you don't find it check also spam and other boxes ("Updates", "Promotions", or "Social" tabs in Gmail).
Tap the "Verify address" button.
Once the withdrawal request is processed, you will receive an email notification. Usually, the transactions are processed quickly, but at times it may take up to 24 hours depending on the network load.
Go to PrimeBit Webtrader, enter "Account properties" section and tap "Withdrawals history" button.
Tap downside arrow to view details of your withdrawal request. 
You can view here your withdrawal request details.