To physically erase; to white or strike out To "expunge" something from a court record means to remove every reference to it from the court file
If you expunge something, you get rid of it completely, because it causes problems or bad feelings. The revolutionaries expunged domestic opposition The experience was something he had tried to expunge from his memory His name was expunged from the record books
Expunging an Rmail file or Dired buffer or a Gnus newsgroup buffer is an operation that truly discards the messages or files you have previously flagged for deletion