Thread locked (and code removed).
Search the board if you must know how to decode base64 encoded PHP scripts - it's been discussed in the past. Also in the past, you'll probably find other threads that I've locked.
If the author (foolishly) used base64 encoding to attempt to obscure their code, then helping you break that obfuscation to edit code that they did not want edited is at the very least unethical and at the worst illegal. You won't find any such help here - sorry!