What you need is a good sound editor like sound forge. Just select the portion when the robotic voice chips in, then go to adjustment then you will notice a wide array of operations that you can perform only on that selected portions. So if theres a voice supress tool there you can use it or else you have to manually figure out the via wave editor.
There's this track I like http://ocrmirror.iiens.net/songs/Castlevania_SotN_TheDevilInside_%28ItaloDiscoMix%29_OC_ReMix.mp3
However, I don't really like the 'robot' voice that plays in some parts. The 'robot' voice is clearly created produced via software, and is not man made vocals.
Is there any way for me to get rid of it?