How to remove all CRLF in file (not replace with LF)

I'd like to remove all carriage returns followed by line feeds (CRLF), such as \r\n in a file. How can I do that? I can't use dos2unix because that replaces CRLF with LF. And I can't use tr because that will also replace any \n that aren't preceded by \r. How can I do this?