Remove Balance

A string consisting only of parentheses $\verb+(+$ and $\verb+)+$ is called a parentheses string. The balanced parentheses strings are defined recursively as follows: - An empty string is a balanced parentheses string. - If $s$ is a balanced parentheses string, then $\verb+(+s\verb+)+$ is also a balanced parentheses string. - If $s$ and $t$ are balanced parentheses strings, then $st$ (concatenati