Cremation is a method of final disposition of a corpse or animal carcass through burning.
https://en.wikipedia.org/wiki/Cremation

Combustion, or burning, is a high-temperature exothermic redox chemical reaction between a fuel (the reductant) and an oxidant, usually atmospheric oxygen, that produces oxidized, often gaseous products, in a mixture termed as smoke.
https://en.wikipedia.org/wiki/Combustion

No oxygen in space, not enough oxygen in the sun to count as burning.

Getting launched into the sun isn't cremation.