Hello and welcome to the forum!
Piece of cake to remove! If he gives you the stock links all you have to do is lift the bike up (quick jack or bike jack) and then remove the two bolts holding the lowering links on and replace the links with the originals. Nothing to it.
And if he's dropped the front end (fork tubes slid up and protruding above top triple clamp) all you have to do is get the front end lifted and then loosen the triple clamp tube pinch bolts (4 on each side? I can't rembember...) and push the tubes back through the top triple clamp until the tops of the tubes are flush with the top of the triple clamp. Retighten the pinch bolts and your almost done. Only other thing you might have to do is loosen the screws that hold the fork tube gaiters on and slide them back up the fork tubes and retighten the screws. Think I had to unbolt my front fender for that.
Sounds like a bit of stuff to do, but it only takes about a half hour when you get the bike lifted up. Make sure it's stable though, it'll hurt if it falls on you!
Enjoy the new to you KLR, great bikes!