Laissez-moi tranquille.
Here's how to pronounce it:
* Laissez: "Lay-say"
* moi: "mwa" (with a very short "wa" sound)
* tranquille: "tran-keel" (with the "l" sound very light)
You can also say:
* Laisse-moi: "Lay-say mwa" (more informal, similar to "leave me" in English)
* Va-t'en! "Va-tan" (meaning "Go away!", more forceful and aggressive)
The choice of expression depends on the context and the level of formality you want to use.