The user CP contains an ignore list which you can add users to.
However you should consider trying to resolve your differences and if necessary appologise to the other person first even if you didnt start it, or explain your position to this person, ignoring someone just furthers the problem in my experience.
Because it is selfish and might leave you happy, but it could leave the other person even more aggravated than before.
If you can get over yourself* for a few moments im sure you can come to an agreement with the party involved allowing you to avoid using such a horrible feature especially on a community board where you should be albe to come to an amicable understanding.
*I say this because ignoring people should never be necessary, unless IMO they are just being abusive/ botting.