0
The space only appears where you added it:
\documentclass{article}
\setlength{\parindent}{0pt}
\begin{filecontents*}{test.csv}
One,Two,Three,Four
a,b,c,d
a,b,c,
a,b,,
a,,,
\end{filecontents*}
\usepackage{datatool}
\DTLloaddb{test}{test.csv}
\begin{document}
\section{Undesired output}
\fre...