Function delete_dpg_from_directory 

pub fn delete_dpg_from_directory(
    dir: &Path,
    group: &str,
    names: Option<&[&str]>,
) -> Result<()>

Delete DPG entries for a specific group from a TRX directory.

When names is None or empty, the entire DPG subdirectory for the group is removed. When names lists specific fields, only those entries are deleted.