This is for those situations where you are trying to find a bunch of lines matching against some Regex and you not only want to remove that match but the line as well.
The regex command being used is: ^.*_.*\R
Breakdown of the command:
^ match start of line
.* match any character as many times until it sees an Underscore ( _ )
.* then again match any character as many times needed until it sees a Line Feed \R
Here you can see the Find box where I have hit count and there is 629 matches and there are 3801 lines in this document
Switched over to the Replace tab and hit Replace All and it got all 629 occurrences found.
Now as you can see there are only 3172 lines in this document meaning that those 629 lines were successfully removed from the document.