Assuming this is the Codeigniter error logging you are referring to, check your config.php for the log_threshold setting and set it to 0 to disable error logging:
/*
|--------------------------------------------------------------------------
| Error Logging Threshold
|--------------------------------------------------------------------------
|
| If you have enabled error logging, you can set an error threshold to
| determine what gets logged. Threshold options are:
| You can enable error logging by setting a threshold over zero. The
| threshold determines what gets logged. Threshold options are:
|
| 0 = Disables logging, Error logging TURNED OFF
| 1 = Error Messages (including PHP errors)
| 2 = Debug Messages
| 3 = Informational Messages
| 4 = All Messages
|
| For a live site you'll usually only enable Errors (1) to be logged otherwise
| your log files will fill up very fast.
|
*/
$config['log_threshold'] = 0;
I usually set it to 1, at least while in development. If you do enable error logging, you should read the error logs and correct the errors if possible, otherwise it is pointless.