Kaddish after slichos without a minyan

I say slichos in a minyan (quorum) of exactly ten people. Sometimes one of the participants leaves before we finish saying slichos. If this happens, can we still say kaddish after slichos?

Dear …

Yes, if there were ten people at the time you said slichos, even if at some point some of them left, you should still say kaddish at the end.

And the same rule applies to other public prayers. Even if some of the ten participants have left, the remaining participants should finish the prayer and say kaddish tiskabel at the end.

Shulchan Oruch, part Orach Chaim, ch. 55, §§2-3; Mishna Berurah, ch. 581, subsection 2