Here's a LuaLaTeX-based solution. It defines a Lua function called hide_stuff which "gobbles" the contents of all figure, table, and lstlisting environments. The only input-related requirements are: (a) the environments' \begin and \end statements must not occur on one and the same input line, and (b) there's only one \begin{...} or \end{...} statement per input line.
Note that it's not necessary to modify or "prime" any of the existing figure, table, and lstlisting environments. All you need to do (besides using LuaLaTeX to compile the document) is to copy the code block from \usepackage{luacode} to \AtBeginDocument{...} into the preamble of your LaTeX document.

% !TEX TS-program = lualatex
\documentclass{article}
\usepackage{listings} % for 'lstlistings' environment
\usepackage{luacode} % for 'luacode' environment
\begin{luacode}
in_group = false -- initialize a Boolean variable
function hide_stuff ( buff )
if string.find ( buff, "\\begin{figure}" ) or
string.find ( buff, "\\begin{table}" ) or
string.find ( buff, "\\begin{lstlisting}" ) then
-- start gobbling
buff = buff:gsub ( "\\begin%b{}.-$" , "" )
in_group = true
elseif string.find ( buff, "\\end{figure}" ) or
string.find ( buff, "\\end{table}" ) or
string.find ( buff, "\\end{lstlisting}" ) then
buff = buff:gsub ( "^.-\\end%b{}" , "" )
in_group = false -- end gobbling
elseif in_group == true then
buff = "" -- keep gobbling
end
return buff
end
\end{luacode}
%% Assign the fuction to LuaTeX's "process_input_buffer" callback
\AtBeginDocument{\directlua{luatexbase.add_to_callback (
"process_input_buffer", hide_stuff, "hide_stuff" )}}
\begin{document}
aaa\begin{figure}
\caption{AAA} \end{figure}
bbb
\begin{table} \caption{BBB}
\end{table}ccc
\begin{lstlisting}
CCC
\end{lstlisting}
uuu\begin{figure} % empty "figure" environment
\end{figure}vvv
\end{document}
listoftables? andlistoffigures? for me, a picture is worth 1,000 words. So I do not see how a figure is not part of document content. Your school have some really strange policy ;) – Nasser Jun 03 '16 at 08:14