How to get a \leftmark without number?

I use the following code to make a header showing current section.

\LoadClass[a4paper]{article}

\RequirePackage{titlesec} 
\titleformat{\section}{\raggedright\large\bfseries}{\,Section\,}{0em}{}
\titleformat{\subsection}[runin]{\raggedright\bfseries}{(\,\arabic{subsection}\,)}{1em}{}

\RequirePackage{fancyhdr}
\pagestyle{fancy}
\fancypagestyle{preContent}
{
    \fancyhf{}
    \fancyhead[L]{\leftmark}
    \renewcommand\headrulewidth{.5pt}   
}
\pagestyle{preContent}

\begin{document}
    \section{secname}
    \subsection{subname}
\end{document}

In the header it shows "1 secname". How can I get something without section number like "secname"?

You could redefine the \sectionmark macro:

\LoadClass[a4paper]{article}

\RequirePackage{titlesec} 
\titleformat{\section}{\raggedright\large\bfseries}{\,Section\,}{0em}{}
\titleformat{\subsection}[runin]{\raggedright\bfseries}{(\,\arabic{subsection}\,)}{1em}{}

\RequirePackage{fancyhdr}
\pagestyle{fancy}
\fancypagestyle{preContent}
{
    \fancyhf{}
    \fancyhead[L]{\leftmark}
    \renewcommand\headrulewidth{.5pt}   
}
\pagestyle{preContent}

\renewcommand{\sectionmark}[1]{\markboth{#1}{}} 
\begin{document}
    \section{secname}
    \subsection{subname}
\end{document}