Hi @Talko
One possible solution is, we could get the header row from the csv file and then update the file with the header row to clean it up. But this is only applicable if you have headers in the csv file.
Here is the sample flow that cleans up all the data rows:
1. Create a scheduled flow and set the recurrence as per your need like time zone, start time etc.:

2. Next, add "Get file content using path" action to read the content of the file in SharePoint library:

I have stored the csv file 'customers.csv' in 'STEW 2' document library, pls modify the path as per your need.
3. Now, add compose action to fetch the header row from the file content. We need to write an expression to get the header row. Expression needs to be added in the expression box as highlighted in the below screenshot:

join(take(split(base64ToString(outputs('Get_file_content_using_path')?['body']?['$content']),decodeUriComponent('%0D%0A')),1),',')
4. Finally, add "Update file" action to clean it up & set the output of compose action in "File content" parameter:

If this helps & solves your problem, please remember to give a 👍 and accept my solution as it will help others in the future.
Thanks