In case you didn't notice, that article is for freshwater.
"Remove one-third of your aquarium's water and replace with fresh, treated tap water."
You do that and it will drop your salinity drastically.
The ONLY way to drop alkalinity in a saltwater system is do water changes with a salt that has a lower alk
level than your tank.
Also, I never heard of alk
having an affect on any fish. Your alk
is high, but not all that high and IMO
it has no affect on fish. If there are any studies done showing such a negative affect, I would be very interested in reading them.