Formal:
* Laissez-moi tranquille. (Leave me alone.) This is the most common and direct translation.
* Laissez-moi en paix. (Leave me in peace.) This emphasizes the desire for quiet and solitude.
Informal:
* Laisse-moi tomber. (Leave me alone / Get lost.) This is a more casual and slightly more forceful expression.
* Fiche-moi la paix! (Leave me alone! / Get lost!) This is a very informal and even rude expression.
Other options:
* Ne m'embête pas. (Don't bother me.) This is a more casual way of saying "leave me alone."
* Ne me dérange pas. (Don't disturb me.) This is a more polite way of saying "leave me alone."
The best phrase to use depends on the situation and your relationship with the person you are talking to.