Formal:
* Уйдите! (Uydite!) - This is the most formal way to say "go away."
* Пожалуйста, уйдите. (Pozhaluysta, uydite.) - This is a more polite way to ask someone to leave.
Informal:
* Убирайся! (Ubiraysa!) - This is a very informal and rude way to tell someone to go away.
* Иди отсюда! (Idi otsyuda!) - This is also informal and means "go from here."
* Прочь! (Proch!) - This is a very strong and abrupt way to say "go away."
More nuanced options:
* Оставьте меня в покое. (Ostavte menya v pokoe.) - This means "leave me alone."
* Не мешайте мне. (Ne meshayte mne.) - This means "don't bother me."
The best way to choose the right phrase depends on your relationship with the person you are speaking to and the situation.