To start the withdrawal procedure you need to make sure you have filled in the KYC form and successfully completed the verification process.
After that, please open the "Withdrawal" section on your account and choose the method you like. Then enter the credentials and confirm the request. The email confirmation of your withdrawal is needed as well!
When all set you may just wait. The regular withdrawal may take from 15-20 minutes to 24 hours depending on the method you use.