Getting rid of feelings is very difficult, there's no magic blue pill to just take to get rid of them.
I suppose the main question is why you would want to? If its because they are a girl as well and people around you aren't accepting of that, or that you are already in a relationship with another person, whatever it is it might actually be easier to deal with that problem rather than trying to "lose feelings" for them.
In the end, time will tell. If its a brief, meaningless crush it will be over before you know it and if its more than that then its probably best you try to deal with the bigger problem that having feelings for this person is causing.