How to clean journalctl logs

The self maintenance method is to vacuum the logs by size or time.

Retain only the past one day:

journalctl --vacuum-time=1d

Retain only the past only 100 MB:

journalctl --vacuum-size=100M

You can also limit the log file size by doing a little configuration in the following file.

...
SystemMaxUse=100M
...

The configuration will run when the server is restarted or restarted of the journald service:

systemctl restart systemd-journald

For more information you can talk about it in the journalctl documentation with the command 'man journalctl'