Python Easy Solution
Code\n\nclass Solution:\n    def smallestString(self, s: str) -> str:\n        new=""\n        flg=0\n        for i in range(len(s)):\n            if s[i]=="a" 
# Code\n```\nclass Solution:\n    def smallestString(self, s: str) -> str:\n        new=""\n        flg=0\n        for i in range(len(s)):\n            if s[i]=="a" and flg==1:\n                new+=s[i:]\n                break\n            if s[i]=="a":\n                new+=s[i] \n            else:    \n               new+=chr(ord(s[i])-1)\n               flg=1\n        if flg==0:\n            new=s[:len(s)-1]+"z"\n        return new\n        \n```
['Python3']