If you are a member landlord, log into your account and locate the tenancy via your deposit management. From here you will be able to raise a repayment request. You will be required to enter when the tenancy ended, how much you wish to claim and the amount you wish to be retuned to the tenant.
If your deposit has been protected by your agent and they are a member of the scheme, contact them to raise this repayment request for you.