Hi Hank yes you can buy and apply a stump killer get it from a garden centre or on line. Drill a few holes on the top of the stump - around the edges pour in the stump killer and cover, It really needs to be done Asap once the tree is down.
It will take some years to rot dowm though. If your uncle can afford it a tree surgeon will take it out with a stump grinder.

The vast majority of conifers die if you cut them down, unlike other trees and shrubs, so there's very unlikely to be any new growth. There isn't anything that will help a stump rot more quickly - but he could get a man out with a tree stump borer to take it out. Tree surgeons usually have someone on the team who will do that.

Whoops, posted at the same time...

A "stump remover" made from saltpeter is supposed to rot the stump faster than Mother Nature does, but I have had mixed results with that.

Thanks once again guys, i'll pass that on to my uncle

Hank your uncle sounds amazing for a 94 yr old! He puts most of the young'uns these days to shame. Men like him are what made Britain Great :-)

Juliet,
You're right J, and he's just realised he might soon need a mobility scooter 'cos of his eyes, so he's mixed a load of concrete to form a ramp up a step into his garage ! Lord knows what he'll do next.

Well, all I can say is I'd hope to be as fit and active as he is at 70, never mind 90 odd...