Everyone of us has any number of biases for the simple reason that we are more comfortable interacting with some people than with others. People consciously and unconsciously differentiate between people, and this is an automatic response by our brains to efficiently differentiate between people or situations without having to analyze them slowly and fully.
Unfortunately, the focus on the differences between people in terms of how they make us feel, creates two groups of people, one positive class of people and other group that makes us less comfortable. Since many of these differentiations are automatic, we are frequently unaware of the old tapes in our minds that put people into one category or the other.
The usual effort to neutralize biases is to make people aware of their bias and the behavior of inclusion or exclusion that results from the bias. We try to use knowledge as the primary technique to create awareness in hopes that awareness changes behavior.
If a bias is simply an unexamined preference without any heavy emotion attached to it, it is possible that some people will have an "aha" reaction as they become newly self aware in the face of factual information. But if the bias is overlaid with powerful memories or desires or unpleasantness, factual knowledge is unlikely to change anything.
In my personal experience, I have always found that where there's no prejudice, that growing familiarity with other people over the course of a few weeks or months eliminates the bias and people perceive others as particular individuals and not as members of a stereotyped group. My advice for those who find themselves uncomfortable which does not lesson over the course of several months is, if it is at all possible move away from those uncomfortable interactions. In other words, get another job or a new group of friends or colleagues.