We all gotta deal with nerves leading into a fight, it's not about removing them just about learning to deal with them. It definitely gets easier with experience and dealing with them is a personal thing - i've developed my own pre-fight mental routine (which I use prior to any stressful events, not just fights) which involves reinforcing a positive attitude whenever anxious thoughts arise about the event.
I largely try not to think about it and just put the thought out of my head when it arises, if it persists I just tell myself to chill out and I benefit the most from reminding myself frequently that the worst-case scenario of getting into the ring is in most cases no big deal and pain or shame is soon forgotton -none of it is the end of the world i.e. you might break a nose / get ko'd / be limping for a few weeks... but you'll mostly get over it very quickly. Maybe I'm sick in the head but the plus side of taking a severe beating in a particular fight is that it can make most of your subsequent ones feel like a walk in the park (not a recommended way to deal with nerves :-).
The physical side of dealing with nerves on fight day and maybe the day before (i.e. adrenaline, shakes, loss of appetite, frequent pissing etc) are largely dealt with by keeping my mind and body as calm as possible - I don't rush anything on the day, get to venue in plenty of time, get gear and wraps etc on then just chill out