How to Skip One Bullet in ITEMIZE?

\documentclass{article}
\begin{document}

You could use an unlabeled item, but the reader has no visual clue that it is a new item 
\begin{itemize}
\item Item 1
\item Item 2
\item[] Item 3
\item Item 4
\end{itemize}

You use a forced linebreak in an existing item
\begin{itemize}
\item Item 1
\item Item 2\\
      Item 3
\item Item 4
\end{itemize}

You use a second paragraph in an existing item
\begin{itemize}
\item Item 1
\item Item 2

      Item 3
\item Item 4
\end{itemize}

These three markups encode three different sentence structures so only
you can say which you need with your real text.
\end{document}

Try like this:

\documentclass{article}
\begin{document}
\begin{itemize}
\item Item 1
\item Item 2
\item[] Item 3
\item Item 4
\end{itemize}
\end{document}

The empty optional argument of \item command will do the trick.