Neither exit nor expulsion from the euro area is possible according to the Lisbon Treaty under which participation in the euro is irrevocable.
It's funny how you can't leave the Euro if you want to or if everyone else wants you to because that's not allowed under the Lisbon Treaty but if you want to give illegal bailouts to bankrupt eurozone countries that's ok even though it's not allowed under the Lisbon Treaty.
Leaving the eurozone is as simple as a national parliament passing a law saying that the country's currency is no longer the euro. The EU Commission will find out soon enough how easy it is.