Credit score has dropped

[Justin Yocom]

Today as I went to refi a house I purchased through an equality loan I came to find out that I have a collection on my credit score that dropped me about 75 points. Lowering me down into the high 600"s. I was unaware I had this bill and it was from the utility department at an old apartment I use to live at. It just got sold to a collection agency and they listed it on my credit. What are some ways I could get this removed from my credit report? Any tips tricks or whatever would be greatly appreciated