Self-Destructing Strings

A binary string is called a *self-destructing string* if it can reduced to an empty string by performing the following operation some number of times (possibly zero): Choose a valid integer $i$ such that the $i$-th character of the current string is different from the $i+1$-th character, and remove these two characters from the string. You are given a binary string $s$. Your task is to convert