Completely left align text in table

I am using tabular and trying to left align text in cells completely to the border of the table. Which parameters do I have to use to delete these white space?

Code

\documentclass[a4paper]{article}
\usepackage{longtable}
\usepackage{multirow,makecell,array}
\begin{document}
\begin{table}[h!]
\begin{tabular}{|L{12cm}C{4cm}}
\textbf{Personal E-mail}: &  \\
\textbf{Mobile phone}:  &    \\
\textbf{Skype}:  &   \\
\textbf{Citizenship}:  & \\
\end{tabular}
\end{table}
\end{document}

• Please add a MWE (start with \documentclass and ending with \end{document} of how you already obtained the above image / document. – albert Jun 11 '18 at 10:48
• \begin{tabular}{|@{}l ...}. – Bernard Jun 11 '18 at 10:48

You can use the alignment operator: @{<LaTeXCode>}. You can replace <LaTeXCode> with any latex code that should be used to separate the column. There is a default setting that is set to some width, but I can't seem to figure it out. Anyways, here is a modified version of your code that removes the space.

That is: I put in, before the first l, an empty specifier: @{}.

\documentclass[a4paper]{article}
\begin{document}
\begin{table}[h!]
\begin{tabular}{|@{}ll}

You can experiment with this: try inserting e.g. @{=} between some of the letters, or @{\hskip 4em}.
Note that I don't know how you defined your L and C, so I just replaced them with ll (both left adjusted). I also removed the width specification in your alignment parameters. Also, I removed the unused packages.