Yes. Also the subdirectories. In both directories.
systemctl stop openhab2
rm -rf /var/lib/openhab2/tmp/*
rm -rf /var/lib/openhab2/cache/*
rm /var/lib/openhab2/config/org/openhab/mail.config
systemctl start openhab2
tail -f /var/log/openhab2/openhab.log -f /var/log/openhab2/events.log
careful with rm -rf
! (better use
rm -ri
to see what you are deleting)