It's Emmett, Clara.
2 seconds sound clip from the Back to the Future Part III movie soundboard.
You can hear this line at 01:12:12.504 in the DVD version of the movie.
Quote context
[...]
- As you reminded me, Marty, I'm a scientist, so I must be scientific about this.
- We shall proceed as planned, and as soon as we return to 1985, we'll destroy this infernal machine.
- Traveling through time has become much too painful.
- Goodbye? Well, where are you going?
- I'm going away. And well, I'm afraid I'll never see you again.
- Emmett!
- Clara, I want you to know that I care about you deeply.
- But I've realized that I don't belong here, and I have to go back where I came from.
[...]