Swedes?

[Annibal]

I have conquered Stralsund and Swedes have no city in mainland but they are still at war with me.
They moved their army into Poland and get supply there? I don't understand this as well. Isn't Poland supposed to be neutral?
Anyway, they came again and besieged cities by Oder like Breslau. What to do to make them get out of war?

[Chaubus]

Kill them all...

They can (barely) resupply in Poland. So if they're running around there can't be that many left. Hunt'em down...

I may be wrong about this but I don't think they ever really leave the war but without an army to annoy you who cares (I did have their leaders leading Austrian or Imperial troops a little later in my last Prussia game).

[Annibal]

So, there is no getting out of war automatically for a single country?

[loki100]

there is a scripted surrender/peace for Sweden - I think that kicks in about 1762. Beyond that no they stay in the war but really aren't much of a threat to you.