Dropping the Availability Group will removeĀ all associated objects .
1.Database (s) will be removed from AG databases
2.Listener will be deleted (object will be dropped from Active Directory).
3.Replicas will be removed from the AG group configuration
USE [master] GO DROP AVAILABILITY GROUP [AG Group Name] GO
Dropping Availability Group
USE [master] GO ALTER AVAILABILITY GROUP [Availability Group Name] REMOVE LISTENER N'ListenerName' GO
Removing Database from Availability Group Databases
USE [master] GO ALTER AVAILABILITY GROUP [Availability Group Name] REMOVE DATABASE [Database Name] GO
Remove Replica from Availability Groups
USE [master] GO ALTER AVAILABILITY GROUP [Availability Group Name] REMOVE REPLICA ON 'Replica Name' GO