How to retrain special class ability

[ahermon]

From "http://www.d20pfsrd.com/basics-ability-scores/more-character-options/retraining" :

"If an archetype or variant class feature replaces the listed class feature, at the GM's discretion you may retrain that alternative class feature for an equivalent variant class feature. For example, inquisitions, which inquisitors can select in place of a domain, and the inquisitor entry below allows you to retrain your chosen domain, so you are allowed to instead retrain an inquisition, swapping it for a domain or another inquisition."

Hello, how would I retrain a special class ability that has been replaced to an archetype? I have the bard archetype Dawnflower Dervish, that replaced bardic knowledge with Dervish Dance. I then later received Dervish Dance from another source, so would like to retrain to get back bardic knowledge, but don't know how to do that in Hero Lab.

Thanks!