If you are a landlord and your management agreement ends with a tenant occupied property you should forward the security deposit to the new landlord or the owner of the property. 

Send a written notice to the tenant that you are no longer the landlord, that you forwarded the security deposit to the new landlord and that the new landlord is now responsible for it. 

In Texas there is a form called the Notice to Tenant of Change in Management and Accountability for Security Deposit.  

This is the best way to handle the security deposit exchange! 

It is also a a good idea to send the Inventory and Condition Form the tenant completed upon move-in so the new landlord knows the condition of the property.