How to remove leading Unciode characters from a file?

I am processing several thousand xml files and have several problematic files.

In each case, they contain lead Unicode characters such as C3 AF C2 BB C2 BF

and EF BB BF

, etc.

In all cases, the file contains only ASCII characters (after the header bytes), so there is no risk of data loss converting it to ASCII.

I am not allowed to change the contents of files on disk, only use them as input to my script.

In the simplest case, I would be happy to convert such files to ASCII (all input files are parsed, some changes are made and written to the output directory where a second script will process them.)

How should I code this? When I try:

with open(filePath, "rb") as file:
    contentOfFile = file.read()

unicodeData = contentOfFile.decode("utf-8")
asciiData = unicodeData.encode("ascii", "ignore")

with open(filePath, 'wt')  as file:
    file.write(asciiData)

      

        
        
        
      

    

I am getting an error must be str, not bytes

.

I have also tried

    asciiData = unicodedata.normalize('NFKD', unicodeData).encode('ASCII', 'ignore')

      

        
        
        
      

    

with the same result. How to fix it?

Or is there any other way to hide the file?