You've just enhanced your equpiment to 15, but found a better Epic...
Don't worry! You can transfer Enhance level or Option Enhance level from one to another.
The process requires Zen or Diamonds.
The maximum number of Option Enhance upon Transfer depends on the material's Option Enhace level and the quality of the target item.
For example, when a material is a magic item with Option Level 30 and the target item is a normal item, the result would be a normal item with Option Level 20.