How can I go to Days Inn City Centre on 99 North Street from Xi'an Railway Station?

You can find Tourist Bus Line 8 (no. 610) near the railway station. Take it and get off at North Street stop at the fourth station. Then walk south for 3min to find your hotel along the street. It is easy to spot. Or directly take a taxi to reach at a cost of CNY9-10.

What if i come from north railway station? How can i go to days inn city center?

Take metro line 2 from North Railway Station to Beidajie Station, Exit C1. Walk south for about 350 yards to the hotel.