journalctl - remove logs of a specific unit

With journalctl, it is possible to remove the old logs, by specifying either the maximum disk space they can use, or the maximum age they can have, or the maximum number of separate journal files (using the options --vacuum-size, --vacuum-time or --vacuum-files).

Is there a way to restrain this deletion to a specific systemd unit ?

journalctl -u <unit> --vacuum-time=2d seems not to work as desired: according to the documentation, -u only works when displaying logs.

After some research I found that you can't delete logs for a specific systemd unit, because the logs are interlaced and if you delete only one unit you'll corrupt the logs, so journalctl doesn't let you.

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

Retain only the past two days:

journalctl --vacuum-time=2d

Retain only the past 500 MB:

journalctl --vacuum-size=500M

Source: https://unix.stackexchange.com/questions/139513/how-to-clear-journalctl