Thank you for your inquiry. Unfortunately there is not "quick" chemical fix to this problem. Assuming you are not dosing anything to raise the level (like a two part solution for example) the best way to lower the levels is by doing large water changes with saltwater that has a lower kH level.
Having said that, some people have found when they run granular ferric oxide (GFO) like Rowaphos or Phosban it can lower the alkalinity levels in their aquarium. You could try running some GFO in the tank to see if that would help some.
You may want to check out this article as well that might help some also:
It talks about the relationship between calcium and alkalinity.
If there is anything else we can do for you please let us know.
Marine Depot Customer Service