If you wish to reassign your Skill or Ability Points, there are items available in the Cash Shop that can do just that.
To find these items, you can use the "Search Item" feature toward the upper right, or go to the "Character Modifications" → "SP/AP Modificaitions" category in the Cash Shop.
Look for the "AP Reset" item to reset your Ability Points. The "SP Reset" item resets your Skill Points. Be sure to purchase the appropriate item for your job level.