The access to the logs files can be found in the first tab of the backend module. The list is automatically updated by java script every few seconds.
Each entry has a unique color to make new files better recognisable,
To prevent these files from clogging up your system, kreXX will only keep 10 files and automatically delete older ones. This value can also be changed the logging option Maximum files in the logfolder to any number bigger than 0.
A description on how to create log files can be found here: Logging
A file can be access by simply clicking on the filename. The trashcan on the right deletes the file.