Is there anything within the range of the fall of that tree? Looks like the split tree is hung very well in the other one, meaning it's going to be a LONG time before wind brings it down.
IF that tree can go anywhere and not hit anything AND nobody really walks around in the fall zone of the tree, leave it. It's going to be a while though, like I said.
If there's nothing in the fall zone of either tree AND people do generally live/work/play in the fall zone it needs to be removed AND the leaning tree is locked heavily with the upright tree(which it looks like it is). I personally would get a rope up in the split tree as far up as I could without risk of breaking off and lock it off against a tree 180º from it's current lean OR cheat slightly towards your falling direction. Pull it just enough to see movement off the other tree with a come along or 5-1 system backed up with a porta-wrap to hold the line in a locked position. The goal here is to keep it from pushing the other tree over as you fall it. Prob 3/4" line here and a big port. Then I would get another line up in the tree it's leaning into and pull 90º from the lean of the split tree. If they have a general lean in one of those two directions pick that way OR the leaning tree is only heavily locked in one direction, make sure you're falling the non-leaning tree so that the leaning tree cannot pull free off the tree you're falling. Again, come along or 5-1(since you can't get machines in there). Get a face cut in it, bore it, set the hinge, tighten up the rope, and cut the strap/trigger. This should keep you out of the danger zone as much as possible and send both trees somewhere safe. The leaner looks like it's compromised enough that it will break off and not hold up the other tree. I've done this on a couple situations like this personally and it worked every time...
You could also, possibly get those two lines in the leaning tree and pull the tree back upright and then pull it over to one direction or the other. Depending on how much pulling power you have and where you can get the lines...I would only attempt this if the other tree is 100% NOT able to be removed for some ridiculous reason. Make sure nobody is within the fall zone of that tree if you do this one though...there's no telling where it could get off to. This would also require some very advanced pulling techniques that allow for re-setting and pulling numerous times on the same line.
IMPORTANT NOTE: I'M NOT THERE!!! This is an initial reaction to 3 pictures on the internet. This plan is in no way fool proof and depends heavily upon how the trees are interlocked and both of their respective leans. I would have to actually see the trees in person to get a solid feeling. Please don't take this advice if you're not 100% confident in your abilities to set lines, lock off lines, put the appropriate amount of tension on those lines, and send those trees where they need to go.
IF there ARE dwellings within the fall zone of either of those trees, go ahead and let someone with a crane piece that bad boy out of there.