Need Publication Targets based on the Target Type (for Event System) using TOM.NET API

Question

I started event system code for my project, where I am getting Target Types for a Publication. Please suggest how to get the Publication Targets based on the Target Type:

My Requirement is : I need to unpublish the component based on the Expiration Date (Metadata field) while publishing the component. I am using following event (PublishEventArgs).

EventSystem.Subscribe<Component, PublishEventArgs>(OnComponentPublishPost, EventPhases.TransactionCommitted);

I am following below snippet code

private void OnComponentPublishPost(Component component, PublishEventArgs args, EventPhases phase)
{
    foreach (PublishingTarget ty in args.Targets)
    {
       string targettype = ty.Id;
    }
}

Here I am getting Target type (ty.id). In unpublishing method I need to pass the Publication Target(targets).

PublishEngine.UnPublish(items, unpublishInstruction, targets);

Please suggest how to get the Publication Targets.