Define command to comment text

Question

I would like to create a command \comment{} which would not compile anything inside of { }.

Why would I not use % or \begin{comment} bla bla \end{comment} from the \usepackage{comment}? Because I want to put some text inside brackets and comment it.

The reason I want to do this is because I have a lot of text in red using \textcolor{red}{bla bla} and I would like to redefine \textcolor{red} so that I can delete everything in red from my document (note that I have a lot of parts in red...).

In a nutshell, my current code

x=x+1 \\
\textcolor{red}{
    I don't want to see this
}

produces this

Instead I would like it to produce this

without having to comment manually every part with \textcolor{red}. I would instead like to redefine this command so that it would comment the text in red.

Note: I want the red text not to be compiled and not to appear invisible, creating blank spaces.

Answer 1

Using the command \suppress from Selectively suppress generation of typeset output to redefine \textcolor

Original document

Redefining \textcolor

\documentclass[12pt,a4paper]{article}

\usepackage{xcolor}
\usepackage{ifthen}

\let\oldtextcolor\textcolor 
\renewcommand{\textcolor}[2]{% <<<<<<<<<<<<<<<<<<<<<<
    \ifthenelse{\equal{red}{#1}}
    {\suppress#2\endsuppress}
    {\oldtextcolor{#1}{#2}}%
}

%% From https://tex.stackexchange.com/a/97360/161015
\makeatletter   
\font\dummyft@=dummy \relax
\def\suppress{%
    \begingroup\par
    \parskip\z@
    \offinterlineskip
    \baselineskip=\z@skip
    \lineskip=\z@skip
    \lineskiplimit=\maxdimen
    \dummyft@
    \count@\sixt@@n
    \loop\ifnum\count@ >\z@
    \advance\count@\m@ne
    \textfont\count@\dummyft@
    \scriptfont\count@\dummyft@
    \scriptscriptfont\count@\dummyft@
    \repeat
    \let\selectfont\relax
    \let\mathversion\@gobble
    \let\getanddefine@fonts\@gobbletwo
    \tracinglostchars\z@
    \frenchspacing
    \hbadness\@M}
\def\endsuppress{\par\endgroup}
\makeatother

\begin{document}

As any dedicated reader can clearly see, the Ideal of practical reason is a
representation of, as far as I know, the things in themselves; as I have shown
elsewhere, the phenomena should only be used as a canon for our under-
standing.

x=x+1 

\noindent \textcolor{red}{I don't want to see this \\ I don't want to see this  \\ I  don't want to see this.}

Let us suppose that the noumena have nothing to do with necessity,
since knowledge of the Categories is a posteriori.

{\color{red} But I want to see this.}

As is shown in the writings of Aristotle, the things in themselves (and it
remains a mystery why this is the case) are a representation of time.

\textcolor{green}{And also to see this.}

 Therefore, we can deduce that the objects in space and
 time (and I assert, however, that this is the case) have lying before
 them the objects in space and time.

\end{document}

From the quoted link

However rules, radical bars, fraction bars and some other things (mostly math) can escape.