Controls :: How To Check PDF Is Comment Enabled Or Not Using C#

My only requirement is to find a selected pdf in a folder is Reader enabled or not, more specifically if usage rights are defined in a way that allows people to add annotations (e.g. comments).

I am doing this in windows application. If I click a button, an event is triggered searching a folder for PDF files. This event needs to check whether or not the PDFs in the folder are Reader enabled for comments. If they are, I need to remove the comment usage rights or revert the PDF back to its original version.

My code can only find PDF files in the folder. I don`t know how to check if the selected PDF is comment enabled or not.  

private void button1_Click(object sender, EventArgs e) {
{
string[] filePaths = Directory.GetFiles("D:myfolderpdffolder");
List<ListViewItem> files = new List<ListViewItem>();
foreach (string filePath in filePaths) {
---need to check comment enabled or not---
}
}
}