Log files are a very important tool to debug issues when needing help from the support team.
After intence use of your favorite application and over a long period, they do take quite some space .
To get an idea of the space used, in a shell, log as root and navigate here :
to get an idea of the space used type this command :
In my case it gave me back this :
I want to clear most log files, but I want to keep the ones generated in the last week just in case I need them soon.
On OS X, use finder to delete the older logs sorting the files by date.
On linux, a similar way to do this is to call konqueror with a command in a shell or through the Application menu of Red Hat.
Since you are already in the log directory type this command:
konqueror . &
Use the Detailed List View found under View - View Mode menu.
Sort by dates and delete old logs.