How long does a red dwarf live for?

A Red Dwarf is a small and relatively cool star, on the main sequence, With a spectral class of either late K or M.

They will last for billions if not trillions of years. Because of the relatively low temperatures, they are very efficient.

Any red dwarf created at the beginning of the Universe, is still in existence and will be for billions/trillions of year.

So there are no "dead red dwarfs" - yet.