Description :There is no command to delete a Launch Window from a multiple Launch Window task.
Cause type: By design Root Cause: This command does not exist.
OS: All OS Version: any
In order to perform the operation via the command line, a possible way would be to change the task to AUTORELAUNCH and then to MULT launch windows again. That way ALL the Launch Windows are deleted. After that, you can add the Launch Windows that you want to keep.