Hi Fateh,

You can safely empty that file if you don't need it for investigating problems with the current (or last) X session (e.g. echo "" > Xorg.0.log). Note that it will start to fill up again.

If the log file consistently grows to large sizes, you may need to find out what's causing this (any repeated errors or warnings in the log?). You may also want to adjust your logrotate settings, so that other log files are pruned more often.