You can combine the every picture style and execute at end picture:
\documentclass{article}
\usepackage{tikz}
\newif\ifhidepics
\hidepicsfalse
%\hidepicstrue % uncomment to hide tikzpicture
\ifhidepics
\tikzset{every picture/.append style={
execute at end picture={
\fill [white] (current bounding box.south west) rectangle (current bounding box.north east);
}}}
\fi
\begin{document}
Something here.
\begin{tikzpicture}
\node at (0,0) {A};
\node at (2,5) {B};
\end{tikzpicture}
More text.
\begin{tikzpicture}
\node at (0,0) {A};
\node at (2,2) {B};
\end{tikzpicture}
Test.
\end{document}