Keep an eye on that rascal. Don't let him run away.

看住他，别让这坏家伙跑了！

《新英汉大辞典》

When you have got an elephant by the hind leg, and he is trying to run away, it's best to let him run.

如果你抓了一头大象的后退，而他又想逃跑，那最好就让它跑掉。

youdao

Buck did not run away, but he did not let them catch him.

巴克不逃走，但也不让他俩抓住它。

youdao

With just a few days to go, Neil Kinnock let his enthusiasm run away with him at the party's final big rally in Sheffield, striking an awkward note that jarred with many voters.

BBC: CONSERVATIVE VICTORY