You can use the Classic Application Wizard to delete Classic applications. Oracle recommends backing up the application before deleting. See Backing Up Applications and Application Databases.
To delete applications:
From Planning, select Administration, then Application, then Delete.
From EPM Workspace, select Navigate, then Administer, then Classic Application Administration, and then Planning Administration. Then select Delete Application.
Select an existing Classic application, and click Delete Application.
At the confirmation message, click OK if you want to proceed with the deletion.