Hi all...new guy here. Help with my apple tree please?

I've got a very gnarled apple tree...that's turning into a sad Charlie Brown tree.
Can anyone tell me what's going on with this...and a possible strategy to bring him back? Thanks all!

It looks like a bad case of agrobacterium gall, and I dont think there is anything that can be done for it. It is more common on trees on dwarfing rootstock,  and in high humidity, low light conditions, and I believe it's best to dig it up and replace it with an unrelated species. It does look too far gone. The bacteria enters through injuries in the graft or roots, and lives in the soil.

So...if I remove the the tree is it ok to plant another apple tree?

I think it would be fine.

Adding an organic mulch like leaves can help build healthy soil and also retain moisture, and checking to see if the soil is well draining could also be a big plus to give the new tree the best chance at surviving and thriving.