Turing machines – Reduced mapping for the problem of useless state in order to prove that its undecidable

I wish to apply a reduction of mapping (many-to-one) with the help of Empty_TM, which accepts nothing, so that the state accept is a useless state. This shows that useless_TM is undecidable.

It is said that a state q in a TM is useless if this state is never reached when M is executed on any string ω ∈ *.

Note: I want the description of the reduction and not the computable function f: * -> Σ *