Hello I am trying to further modify my TOC. I got an answer here as to how I could remove the \section numbers on the left side of the TOC and now I would like to expand that. I would like to remove the left-hand numbering for \subsection and \subsubsection as well but I do not know how. (I also want to keep these numbers out of the document and I am using \def\sectionformat{} to do that)

Also, my TOC is slightly over one page and so I would like to adjust the spacing from 2 to 1.5, is there any way to do this?

\documentclass[12pt, a4paper, twoside]{article}
\usepackage[margin=1in,bindingoffset=15.5mm,heightrounded]{geometry}
\usepackage[T1]{fontenc}
\usepackage[notes]{biblatex-chicago}
\usepackage{filecontents}
\usepackage{microtype}
\usepackage{url}
\usepackage{makeidx}
\usepackage{indentfirst}
\usepackage{setspace}
\usepackage{chngcntr}\counterwithin*{footnote}{section}
\newcommand*{\textsubscript}[1]{$#1{}$}
\DefineBibliographyStrings{english}{references = {Works Cited}}
\DeclareBibliographyCategory{primary}
\makeindex
\makeatletter
\let\latexl@section\l@section
\def\l@section#1#2{\begingroup\let\numberline\@gobble\latexl@section{#1}{#2}\endgroup}
\def\sectionformat{}
\def\subsectionformat{}
\def\subsubsectionformat{}
\makeatother
\author{}
\title{\vspace*{36 pt}\textbf{\emph{\Huge{Big Important Title}}}\vfill}
\date{}
\begin{document}
\tableofcontents
\section{Part I}
Hello World
\end{document}

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If you want no number starting from subsections downwards either in the document and in the TOC, the simplest way is to say

\setcounter{secnumdepth}{1} % only chapter and sections will be numbered
\setcounter{tocdepth}{3}    % entries down to \subsubsections in the TOC

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Thank you, it worked great! Do you know how to adjust the line spacing in the TOC as well? – Mike Stumpf Jul 15 '12 at 20:23
@Wrigley242 Just say \begingroup\onehalfspacing\tableofcontents\par\endgroup or, better, don't use increased spacing at all (if you can). – egreg Jul 15 '12 at 20:33
Perfect. Thank you. – Mike Stumpf Jul 15 '12 at 20:35