Closet door doesn't close completely from the top side - IKEA closet and hinges
Use a long straight edge (4-6' long, depending on the height of the cabinet) on the door (maybe use the level you used to ensure that the cabinet itself was vertical) to ensure that the door itself is flat and not warped. Though they seem to take pretty good care of these in shipping, things happen.
If you're certain the door is flat, use an accurate ruler to ensure that the mounting holes in the cabinet wall are all the same distance from the front edge of the cabinet. Despite these all being machine made, it's possible for the holes to be misdrilled. I recently purchased &amp; assembled a (non-IKEA) flat-pack armoire and both side panels were incorrectly drilled - the bottom 2 door hinges would mount, but the top ones wouldn't. They sent me replacement sides and all is good now.
It is possible, BTW, to remove the screws for the hinges. With a little care you can install them several times if necessary. The particle board these are made of will get chewed up, but it is doable (again from personal experience). If you determine that the problem is with the door, you should be able to exchange it. Remove the screws from the door since it (and any damaged holes) is going to be returned.