Why are my emotions having input on my decisions? How can I eliminate them or suppress them for good?

It's not a good idea to eliminate your emotions. Your emotions are formed by taking in a large variety of data, far more than you can process sequentially, and coming to an overall positive or negative view of something. While it is good not to let them come before logic, a good or bad 'feeling' about something can alert you to that there is something you haven't considered - something your logical mind, focusing on one line of thought at a time, hasn't yet had time to consider, but which your emotional mind, being able to consider many things at a time, is aware of.