What happens at the release of the old?

The elderly actually get euthanized. There is a small celebration first,

[The] telling of his life … is always first. Then the toast. We all raised our glasses and cheered. We chanted the anthem. He made a lovely good-bye speech. And several of us made little speeches wishing him well. (ch 4)

The peson then walks through a special door to the Releasing Room. The elderly are pretty happy before they enter the releasing room. They have no clue they are going to die.