When using Org-mode and its LaTeX export BibTeX or Biblatex is often used to handle references. In that case the LaTeX command \\printbibliography is often included
\\printbibliography
* References :PROPERTIES: :UNNUMBERED: t :END: \printbibliography[heading=none]
There is an easier way to solve this. Just add an "unnumbered" properties to the heading and it will be exported without any numbering.