eoan:

ubuntu@lp1858412-e:~$ dpkg -l systemd|grep systemd
ii  systemd        242-7ubuntu3.7 amd64        system and service manager
ubuntu@lp1858412-e:~$ du -sh /var/log/journal/remote
273M	/var/log/journal/remote
ubuntu@lp1858412-e:~$ sudo journalctl -D /var/log/journal/remote --vacuum-size=10M
ubuntu@lp1858412-e:~$ du -sh /var/log/journal/remote
273M	/var/log/journal/remote


ubuntu@lp1858412-e:~$ dpkg -l systemd|grep systemd
ii  systemd        242-7ubuntu3.8 amd64        system and service manager
ubuntu@lp1858412-e:~$ du -sh /var/log/journal/remote
273M	/var/log/journal/remote
ubuntu@lp1858412-e:~$ sudo journalctl -D /var/log/journal/remote --vacuum-size=10M
Deleted archived journal /var/log/journal/remote/system@106304fba7e24f4eaa633c524dee66e4-0000000000000001-0005a4f93261040f.journal (8.0M).
Deleted archived journal /var/log/journal/remote/user-1000@63c462cb3bfe42d8aae1a91b4d2711a6-0000000000000435-0005a4f935a960b5.journal (8.0M).
Deleted archived journal /var/log/journal/remote/system@106304fba7e24f4eaa633c524dee66e4-00000000000013e8-0005a4fb05e4c7ef.journal (8.0M).
Deleted archived journal /var/log/journal/remote/system@106304fba7e24f4eaa633c524dee66e4-00000000000013ec-0005a4fb092ed6af.journal (8.0M).
Deleted archived journal /var/log/journal/remote/user-1000@63c462cb3bfe42d8aae1a91b4d2711a6-00000000000014fe-0005a4fb271141e0.journal (8.0M).
Deleted archived journal /var/log/journal/remote/system@106304fba7e24f4eaa633c524dee66e4-0000000000001941-0005a4fb29d41b99.journal (8.0M).
Deleted archived journal /var/log/journal/remote/user-1000@63c462cb3bfe42d8aae1a91b4d2711a6-0000000000001993-0005a4fbc19b8de5.journal (8.0M).
Deleted archived journal /var/log/journal/remote/system@106304fba7e24f4eaa633c524dee66e4-0000000000001ca3-0005a4fbc267c680.journal (8.0M).
Deleted archived journal /var/log/journal/remote/system@106304fba7e24f4eaa633c524dee66e4-0000000000001dd8-0005a4fbc464346b.journal (8.0M).
Deleted archived journal /var/log/journal/remote/user-1000@0110cef9e4a8457ba44cf2e309034570-0000000000001de1-0005a4fbc5523608.journal (8.0M).
Deleted archived journal /var/log/journal/remote/system@106304fba7e24f4eaa633c524dee66e4-0000000000001df2-0005a4fbc93c71d7.journal (8.0M).
Deleted archived journal /var/log/journal/remote/system@106304fba7e24f4eaa633c524dee66e4-0000000000001df4-0005a4fbf7e6a339.journal (8.0M).
Deleted archived journal /var/log/journal/remote/system@106304fba7e24f4eaa633c524dee66e4-0000000000001df7-0005a4fc2dbe7958.journal (8.0M).
Deleted archived journal /var/log/journal/remote/system@106304fba7e24f4eaa633c524dee66e4-0000000000001dfe-0005a4fc2f8efc30.journal (8.0M).
Deleted archived journal /var/log/journal/remote/system@106304fba7e24f4eaa633c524dee66e4-0000000000001dff-0005a4fc4181be1d.journal (8.0M).
Deleted archived journal /var/log/journal/remote/system@106304fba7e24f4eaa633c524dee66e4-0000000000001e02-0005a4fc7bce3298.journal (8.0M).
Deleted archived journal /var/log/journal/remote/system@106304fba7e24f4eaa633c524dee66e4-0000000000001e06-0005a4fc7dddc828.journal (8.0M).
Deleted archived journal /var/log/journal/remote/system@106304fba7e24f4eaa633c524dee66e4-0000000000001e09-0005a4fc91a3f7ed.journal (8.0M).
Deleted archived journal /var/log/journal/remote/system@106304fba7e24f4eaa633c524dee66e4-0000000000001e10-0005a4fc9373a53e.journal (8.0M).
Deleted archived journal /var/log/journal/remote/system@106304fba7e24f4eaa633c524dee66e4-0000000000001e11-0005a4fca1309488.journal (8.0M).
Deleted archived journal /var/log/journal/remote/system@106304fba7e24f4eaa633c524dee66e4-0000000000001e6e-0005a4fca379da83.journal (8.0M).
Vacuuming done, freed 168.0M of archived journals from /var/log/journal/remote.
ubuntu@lp1858412-e:~$ du -sh /var/log/journal/remote
105M	/var/log/journal/remote