Borrar una restricción DEFAULT si conocer el nombre - SQL SERVER

DECLARE @ObjectName NVARCHAR(100)

SELECT @ObjectName = OBJECT_NAME([default_object_id]) 

FROM SYS.COLUMNS

WHERE [object_id] = OBJECT_ID('[dbo].[Certificados]') AND [name] = 'Print_QR';

EXEC('ALTER TABLE [dbo].[Certificados] DROP CONSTRAINT ' + @ObjectName)

GO