YOU SAID:

that person needs to go away

INTO JAPANESE

その人が離れて行く必要があります。

BACK INTO ENGLISH

You need that person to go away.

INTO JAPANESE

あなたはその人を離れなければなりません。

BACK INTO ENGLISH

You have to leave that person.

INTO JAPANESE

あなたはその人を残しています。

BACK INTO ENGLISH

You are leaving that person.

INTO JAPANESE

あなたはその人を去っています。

BACK INTO ENGLISH

You are leaving that person.