slip away
steal away
sneak away
sneak off
sneak out

If they went on by he would sneak away behind them.

For the time being he decided to sneak away instead.

The people who did this just wanted to be able to sneak away.

"And that is for trying to sneak away while I was gone."

"If he has to sneak away instead of break out, a day isn't too long to wait."

And who would they be, sneaking away in the night?

They must try to sneak away in the moment when no one would notice, but of course, everyone knew it.

If they tried to sneak away and were spotted, they'd probably be cut down.

Now wash your face and go to sleep, because we're going to sneak away in the middle of the night.

Don't go running off into space, thinking you can just sneak away without anyone knowing; because the League always knows.