Most of these skills determine the maximum tech level of various types of gear that you can use, these cannot be reset.
Advanced Class Subskills require Advanced Skill Points, which you can get by training your class skills above level 20 in Lyceum. Each subskill costs 1 Advanced Skill Point.
These skills need 78 Gold Bars and 9 Platinum Bars total to train.
Trained in Lagrange
Also trained in Lagrange
Imperial Seal Skills