He never removed it.

Yes, actually, Magneto did once remove Wolverine's adamantium. In response, Xavier lashed out with a powerful psychic assault that wiped Magneto's mind, and left him a drooling vegetable for months. Wolverine nearly died, but his healing factor saved him. Once the adamantium was out, Wolverine discovered that his healing factor was greatly increased. And soon, in a conflict with Cyber, Wolverine popped bone claws from his hands for the first time, proving that claws were one of his mutant powers all along--they were just covered with adamantium, like the rest of his bones. Of course, the bone claws were much less durable and would tend to break off in combat, which hurt like nobody's business. But Wolvie's used to pain and would just grow more. Soon after, Wolverine was captured by a rather obscure character called Genesis. Genesis was really Tyler, Cable's son from the future who had gone insane and evil. Tyler wanted to be the heir to Apocalypse, and so created armor that kind of made him look like Apocalypse. Genesis gained control of the Dark Riders, and then captured Wolvie's old foe Cyber, who had admantium cybernetic arms. Genesis threw Cyber into a pit where these flesh-eating beetles...well, let's just say when it was all over, the cybernetics were picked clean. Genesis then tried to re-bond the adamantium to Wolverine's bones, but it didn't take--Wolvie's healing factor went into overdrive, which put him into the mother of all berserker rages, during which he killed Genesis and most of the Dark Riders (except for Tusk, of course, the only slightly cool one). Years later, the real Apocalypse returned and captured Wolverine. He pitted Wolverine against Sabretooth, who at that point had adamantium on his bones (it isn't clear where Sabretooth got this treatment, but it was around the time that he was working with the government-sponsored X-Factor, so Weapon X is the most likely supplier). The winner of the contest would get to be Apocalypse's new horseman, Death. Wolverine didn't want to be death, but reasoned that Sabretooth would be even more murderous and unstoppable as Death, so Wolvie gave it his all and beat Sabretooth. As a reward, Apocalypse removed Sabretooth's adamantium and bonded it to Wolvie's skeleton, and this is the adamantium Wolverine has had ever since. Later, Sabretooth started dying because his body could not adjust to the absence of the adamantium. Gambit found him and arranged for Sabretooth's old partner, the Constrictor, to part with his adamantium tendrils, which were melted down and bonded to Sabretooth's bones. So now both Sabretooth and Wolverine have adamantium.

O.k I have no idea how you got wolverine's mutant power is the claws and his power is his HEALING ABILITY dumb F$#@. I have no Idea how he got his "metal" back into him but he did it some how and trust me on this one he is older than Xavier Magneto and old ppl put together and the reason Sabertooth doesn't like wolverine is because they are brothers and when wolverine got the "metal" sabertooth wanted it too so he always wanted to prove that he was better than his little brother