如何制作宏脚本来删除所有字符串 \answer{*}

Question

如何制作一个宏脚本来删除所有字符串\answer{*}。例如：

\begin{problem}
    question 1: what day is it today?
    \answer{
    To day is \textbf{Monday}.
    }
\end{problem}


\begin{problem}
    question 2: what day is it today?
    \answer{
        To day is \textbf{Tuesday}.
    }
\end{problem}

\begin{problem}
    question 3: what day is it today?
    \answer{
        To day is \textbf{Wednesday}.
    }
\end{problem}

结果是：

\begin{problem}
    question 1: what day is it today?
\end{problem}


\begin{problem}
    question 2: what day is it today?
\end{problem}

\begin{problem}
    question 3: what day is it today?
\end{problem}