I had to make that choice once unfortunately. It's extremely hard. I guess you can say yes you can, but it comes at a cost to your feelings.

To stop loving someone you have to become very numb across your life as a whole, and lower your overall sensitivity.

I had to stop loving a girl because she didn't love me and the whole thing was going nowhere. I had to get rid of the pain of the rejection, forget the fact that she just ignored me, and I had to "kill" my feelings for her.

As a result, today I feel hardly any love at all, for anyone or anything. I have become a very detached individual and an observer instead of a participant in life. I am mostly numb and find it hard to even work on something that I used to love before.

So, come to think of it, the answer is actually maybe no in that sense, because it can be done but by giving up on love totally. So, yes, you stopped loving the person, but only because you stopped loving all together.