Simple 'No way' would fit, I think. 'Spare me' can be used, I suppose, but it don't reflect the newances of the Russian 'Нет уж, увольте'.

Уволить literally (and originally) means 'to set/make free' or 'to release/to let go' (from воля = freedom and/or will) or 'to fire/to dismiss' (present and more common a meaning).