Use sp_downgrade to downgrade Adaptive Server 15.7 ESD #2 to an earlier version.
1> sp_displayaudit 2> go
Downgrade from Adaptive Server 15.7 ESD #2 Cluster Edition to Adaptive Server Cluster Edition versions 15.5, 15.0.3, and 15.0.1.5. Downgrading to earlier versions of Adaptive Server is not supported.