I've been really thinking about disenchanting the card, the only use for it, is it's instant win condition.
I've played the OTK a while but it seems boring to me, but I really like the card art and the fact that it's a death knight. But it's in wild now and I would love to have kel'thuzad again, disenchanted that card on the first rotation :( I also like to play a full legendary deck in wild from time to time and uther shines in that deck.
It's your decision, so do what you think is right.
I don't think Uther will ever be more than a somewhat viable instant-win condition that might gain more consistency over time, or disappears entirely because of some changes we can't foresee. On the one hand, statistically, Paladin should get more and more and more tools to prolong a game, as Hearhstone continues to develop. But who knows if there will ever be a card that prohibits both players to use their hero power for the rest of the game or aggressive decks reaching a point where it's downright impossible to survive 10 turns. Not to mention that Team5 just stated very explicitly that Paladin won't be getting board clears anytime soon, which is already one of the main problems with staying alive for the class.
KT, on the other hand, is still more of a "fun" card after all these years, that can be good in some few decks. I think if we ever get to a point where KT would be actually good and a powerful card, there might be better alternatives, like Catrina Muerte for Priest. But it's still less limited in use than Uther. If you value that more, that's your answer.
However, keep in mind that you think about disenchanting a Wild legendary for the sake of crafting a Wild legendary you disenchanted ealier. I don't know why you disenchanted KT in the first place, but better be safe than sorry before you make the same mistake again. Collecting 1600 dust can take a while, as you probably realize right now. If possible, I would delay the decision for now. If KT is the only card you want right now and for the time being, keep grinding for dust until you can afford it without sacrifices.