I'm trying to remove all users from an AD group with the following code:

private void RemoveStudents() {
        foreach (DirectoryEntry childDir in rootRefreshDir.Children) {
            DirectoryEntry groupDE = new DirectoryEntry(childDir.Path);

            for (int counter = 0; counter < groupDE.Properties["member"].Count; counter++) {
                groupDE.Properties["member"].Remove(groupDE.Properties["member"][counter]);
                groupDE.CommitChanges();
                groupDE.Close(); 
            }             
        }      
    }    

The rootRefreshDir is the directory that contains all the AD groups (childDir).

What I'm finding here is that this code does not behave correctly. It removes users, but it doesn't do it after the first run. It does "some". Then I run it again, and again, and again - depending on how many users need to be deleted in a group. I'm not sure why it's functioning this way.

Can someone help fix this code or provide an alternative method to delete all users in a group? Thanks!