You can (probably) use
Additional commands that are executed after the service is stopped.
This includes cases where the commands configured in
used, where the service does not have any
ExecStop= defined, or where
the service exited unexpectedly. This argument takes multiple command
lines, following the same scheme as described for
ExecStart=. Use of
these settings is optional. Specifier and environment variable
substitution is supported. Note that – unlike
ExecStop= – commands
specified with this setting are invoked when a service failed to start
up correctly and is shut down again.
It is recommended to use this setting for clean-up operations that
shall be executed even when the service failed to start up correctly.
Commands configured with this setting need to be able to operate even
if the service failed starting up half-way and left incompletely
initialized data around. As the service's processes have been
terminated already when the commands specified with this setting are
executed they should not attempt to communicate with them.
Note that all commands that are configured with this setting are
invoked with the result code of the service, as well as the main
process' exit code and status, set in the
$EXIT_STATUS environment variables, see systemd.exec(5) for