[AmigaBlizzard]

Or do you want to delete the "Leader" line from all your accounts as it's no longer needed?
Then you should only ignore this line when loading the file (when player logs in) and don't save it anymore when the player logs out.

Then the line should delete itself when a player logs in and out again.
Unless you use some INI parser, then you might check if your system can delete variables from a file.