Removing arrow tips in TikZCD

Section 1.2 of tikz-cd documentation details this; in particular, it sounds like you might want dash

% arara: pdflatex
\documentclass{standalone}
\usepackage{tikz-cd}

\begin{document}
\begin{tikzcd}
  A \arrow[dash]{r} & B
\end{tikzcd}
\end{document}

Following the comments, you can apply dash to every arrow for the current environment using

\begin{tikzcd}[every arrow/.append style={dash}]
  A \arrow{r} & B
\end{tikzcd}