Removing box around solution

Question

My inital problem was finding a solution which allowed me to collect all answers in the exam document class and have them printed at the end of an document. I found this solution click, which satisfies my needs almost perfectly, however, I don't like one thing:

I don't want the box around the solutions! I've tried finding which command actually causes that box to be printed, however, as someone who just started using LaTeX, I couldn't find anything.

I'd really appreciate if someone could guide me to a solution :)

Thanks in advance!

Below, I indicated the whole code from the above-linked thread, for your convenience :):

\documentclass[a4paper]{exam}
\usepackage{xparse}
\printanswers
\ExplSyntaxOn
% Counters are not reset on \end{parts} so I add code to reset them
\tl_put_right:Nn \endparts { \setcounter{partno}{0} }
\tl_put_right:Nn \endsubparts { \setcounter{subpart}{0} }
\tl_put_right:Nn \endsubsubparts { \setcounter{subsubpart}{0} }
\seq_new:N \l_exam_endprint_seq
\seq_new:N \l_exam_endprint_labels_seq
\tl_new:N \l__exam_endprint_temp_tl
\NewDocumentCommand \WriteAnswer { +m } {
    \seq_gput_right:Nx \l_exam_endprint_labels_seq {\arabic{question}\alph{partno}\roman{subpart}\greeknum{subsubpart}} \seq_gput_right:Nn \l_exam_endprint_seq { #1 } 
}
\NewDocumentCommand \EndPrintAnswers { } {
    \seq_map_inline:Nn \l_exam_endprint_seq {
        \seq_pop_left:NN \l_exam_endprint_labels_seq \l__exam_endprint_temp_tl
        \renewcommand{\solutiontitle}{\noindent\textbf{Solution~\l__exam_endprint_temp_tl}:\enspace}
        \begin{solution} ##1 \end{solution}
    }
}
\ExplSyntaxOff
\begin{document}
\begin{questions}
\addpoints \question
\begin{parts}
    \part This is the first part of question one.
    \WriteAnswer{This is the solution to part one of question one.}
    \part This is the second part of question one.
    \begin{subparts}
        \subpart This is the first subpart of the second part of question one.
        \WriteAnswer{This is the solution to the first subpart of part two of question one.}
        \subpart
        \begin{subsubparts}
        \subsubpart This is the first subsubpart of the second subpart of the second part of question one.
        \WriteAnswer{This is the solution to the first subsubpart of the second subpart of the second part of question one.}
        \end{subsubparts}
    \end{subparts}
    \part This is the third part of question one
    \WriteAnswer{This is the solution to part three of question one.}
\end{parts} 
\addpoints \question This is the second question.
    \WriteAnswer{This is the solution to question two.}
\end{questions}
\EndPrintAnswers
\end{document}

Answer 1

Welcome to TeX.SE...

The tag \unframedsolutions does the trick, and the MWE is:

\documentclass[a4paper]{exam}
\usepackage{xparse}
\printanswers
\unframedsolutions
\ExplSyntaxOn
% Counters are not reset on \end{parts} so I add code to reset them
\tl_put_right:Nn \endparts { \setcounter{partno}{0} }
\tl_put_right:Nn \endsubparts { \setcounter{subpart}{0} }
\tl_put_right:Nn \endsubsubparts { \setcounter{subsubpart}{0} }
\seq_new:N \l_exam_endprint_seq
\seq_new:N \l_exam_endprint_labels_seq
\tl_new:N \l__exam_endprint_temp_tl
\NewDocumentCommand \WriteAnswer { +m } {
    \seq_gput_right:Nx \l_exam_endprint_labels_seq {\arabic{question}\alph{partno}\roman{subpart}\greeknum{subsubpart}} \seq_gput_right:Nn \l_exam_endprint_seq { #1 } 
}
\NewDocumentCommand \EndPrintAnswers { } {
    \seq_map_inline:Nn \l_exam_endprint_seq {
        \seq_pop_left:NN \l_exam_endprint_labels_seq \l__exam_endprint_temp_tl
        \renewcommand{\solutiontitle}{\noindent\textbf{Solution~\l__exam_endprint_temp_tl}:\enspace}
        \begin{solution} ##1 \end{solution}
    }
}
\ExplSyntaxOff
\begin{document}
\begin{questions}
\addpoints \question
\begin{parts}
    \part This is the first part of question one.
    \WriteAnswer{This is the solution to part one of question one.}
    \part This is the second part of question one.
    \begin{subparts}
        \subpart This is the first subpart of the second part of question one.
        \WriteAnswer{This is the solution to the first subpart of part two of question one.}
        \subpart
        \begin{subsubparts}
        \subsubpart This is the first subsubpart of the second subpart of the second part of question one.
        \WriteAnswer{This is the solution to the first subsubpart of the second subpart of the second part of question one.}
        \end{subsubparts}
    \end{subparts}
    \part This is the third part of question one
    \WriteAnswer{This is the solution to part three of question one.}
\end{parts} 
\addpoints \question This is the second question.
    \WriteAnswer{This is the solution to question two.}
\end{questions}
\EndPrintAnswers
\end{document}