To just reduce the weight, thin any time. For best fruit and good return bloom, thin as early as possible. Sevin insecticide will thin some if sprayed about the time apples are 1/4 to 1/2 inch. Mix up a strong solution, highest label rate. The other thinning agents aren't readily available.

With all the energy going into producing too many apples this year next year should guarantee a light crop, as the fruiting buds forming now for next year will be short changed. Thinning early is the solution, but most Golden Delicious are standards and so large a tree that proper thinning is too much for most of us. Check with the farm supply for a thinning spray. Al

I think you're looking for something along the lines of this product, called Amid-Thin. I know they used to sell this type of thing around here at garden centers for people that didn't want fruit on crabapples, but I haven't noticed it in the past few years.

This site if from Canada, and is dated this past July, so I guess it's still being made and sold at least in Canada, don't know about in the US.

Here is a link that might be useful: Amid-Thin Canadian product label

Thin more, and then be a hero and take all your extra apples down to the food bank.