Reduce size of folder /var/log/journal and /var/cache/abrt-di in Ubuntu

/var/log/journal

Check disk usage

journalctl --disk-usage

Change configuration

Edit /etc/systemd/journald.conf

SystemMaxUse=50M

Restart service

systemctl restart systemd-journald.service

/var/cache/abrt-di

Check Max size of the log files

$ grep -i size /etc/abrt/abrt.conf 
# Max size for crash storage [MiB] or 0 for unlimited
MaxCrashReportsSize = 1000

Check Max size of /var/cache/abrt-di

$ grep -i DebugInfoCacheMB /etc/abrt/plugins/CCpp.conf
DebugInfoCacheMB = 2000

References

Can I remove files in /var/log/journal and /var/cache/abrt-di/usr?