Q: How to disable indentation in particular section in LaTeX? I need to disable indentation in only one section of my document (subsection, to be specific). How can I do that?
Default indentation is provided by indentfirst package.

A: \noindent I think is what you want.

A: It depends on how pervasively you want to eradicate the indentation.  But the first thing I'd try is setting \parindent to 0pt:
Some text with normal indentation...

{\parindent0pt % disables indentation for all the text between { and }

Text with no indentation.

Still no indentation.

}% restore indentation

Indented again.


A: An environment that sets the indent could be a possible solution? You define it in the preamble like:
\newlength\mystoreparindent
\newenvironment{myparindent}[1]{%
\setlength{\mystoreparindent}{\the\parindent}
\setlength{\parindent}{#1}
}{%
\setlength{\parindent}{\mystoreparindent}
}

In your document you would then write something like:
\begin{myparindent}{0pt}
This paragraph is not indented, ehm well, actually it is indented by 0pt
which is the same as not indented.

And this paragraph neither\ldots
\end{myparindent}

Or if you want a large paragraph indent
\begin{myparindent}{5cm}
The first line of this paragraph is indented by 5 cm.

And so is the first line of the next paragraph.
\end{myparindent}

