This route is described in Dick Ingraham's guide as the NW ridge http://web.nmsu.edu/~amato/ingrahamguide/index.html. It involves some meandering and plenty of route-finding, which makes it exemplary of Organ Mountain climbing. Doubtless, there are scores of variations on this route, but most of them offer good climbing on decent rock. The overall character of the route id to find the path of least resistance. The first pitch scrambles up some easy ground on the west side of the Citadel, to the right of The Nose. Pitch 2 traverses left on the large ledge system taking you to the north side of the Citadel. Pitch 3-5 work up the ridge whichever way seems best. If you stay left from pitch 2, you end up doing more face climbing. One can easily end up facing a difficult move, or not having pro on this face, but there are many possible lines. The climbing eases closer to the top, becoming low-5th, or even 4th class for the last pitch. At the summit is a nice desert garden. relax and read the summit register under the juniper tree.
Location
Path of least resistance up the NW ridge of the Citadel. An easy descent can be made on the north side, but requires some scrambling/down-climbing. Scramble down off the summit and back to a small, exposed ledge on the north face over a 100' slab. Find the poot slings and you can do a single rope rappel to gain a large ledge beneath the slabs. The east side of this ledge is a dirty gully which can be scrambled down. While you are scrambling down check out the cool roof system to your right, several harder lines exist.
Protection
Standard rack. Some topos show fixed pins and bolts, but depending on how you meander up to the top, you may not run across these. There are some nice comfy belay ledges that stay shady most of the morning.