algorithm2e command \procedure already defined

If you're referring to coin.cls that forms part of the Computational Intelligence group at Dalhousie University's Department of Computer Science, then the solution is fairly straight-forward if you want to keep using algorithm2e: set the \procedure and \endprocedure macros to \relax.

% https://projects.cs.dal.ca/ci/latex/template-files/coin.cls
\documentclass{coin}

\let\procedure\relax
\let\endprocedure\relax
\usepackage[algo2e]{algorithm2e}

\begin{document}

\begin{algorithm2e}[H]
  \SetAlgoLined
  \KwData{this text}
  \KwResult{how to write algorithm with \LaTeX2e }
  initialization\;
  \While{not at end of this document}{
    read current\;
    \eIf{understand}{
      go to next section\;
      current section becomes this one\;
    }{
      go back to the beginning of current section\;
    }
  }
  \caption{How to write algorithms}
\end{algorithm2e}

\end{document}

So if you're not going use these theorem-like structures, then there shouldn't be any other conflict.

Both the algorithm and procedure environments are predefined inside the coin document class as theorems:

\newtheorem{algorithm}{Algorithm}%[theorem]
%...
\newtheorem{procedure}{Procedure}%[section]

The algorithm environment definition is avoided by using the algo2e option of algorithm2e, which creates an algorithm2e float rather than algorithm.