Extract the 123.xlsx to a folder (is a ZIP file) 
Open the protected sheet to an editor 
remove the SheetProtection tag and save the file. Go back, select all (CTRL+A) 
Right click > Send To > Compressed folder (aka ZIP).
Final open the 123.xlsx unprotected.
origin - https://www.pipiscrew.com/?p=14498 unprotect-excel-sheet