rename to .zip
open xl\worksheets
find and delete the sheetprotection hash, everything in <>
It will look something like:
<sheetProtection algorithmName=”SHA-512″ hashValue=”x9RyFM+j9H4J3IFFhsHo3q1kQkuLydpJlLh2mdvfvk15He/Yps8xizWt/XkAJ//g+TyqgcU+8o1QBjQvKDqIzg==” saltValue=”57YXDPnVjawU5s1nGyT8fQ==” spinCount=”100000″ sheet=”1″ objects=”1″ scenarios=”1″/>