First rotate the logs, using the following command.
This should rotate the log files (so kern.log becomes kern.log.1); and you can then delete kern.log.1 etc to free up the disk space.
Then delete the old log files.
sudo find /var/log -type f -name "*.1" -delete
If thewre are too many old archived log files, delete them as well.
sudo find /var/log -type f -name "*.gz" -delete
Check Journalctl Logs
Vacuum Logs older than a few days
or Vacuum Logs keeping the minimum size
You can control the size of this directory using this parameter in your