I’ve spent sooo long trying to fix this mesh. I’ve tried ZRemesher, close holes, smoothing it out, etc. I just want to cut it off or something so I can continue this sculpt.
Another thing, I have around 354K polys but I’d like to drop this back down to around 50k polys. There are no lower sub levels that I can go to for some reason, I’ve tried re meshing with the half-poly thing bit it will only go so low before not halving any further.
Ah, the joys of learning ZB. 
I tend to stay away from using ZRemesher because it will toss out your subdivision levels as you’ve experienced.
As far as getting rid of the bad geo, you can try to hide the bad geo(ctrl-shift-alt + drag) and then “delete hidden” and see if that works for you. Afterwards you may have to “fill hole”.
If you’re doing concept sculpting then using ZRemesher may be ok but for many projects, its best not to use it so that you can keep your subdivision levels. They make it much easier to sculpt than without. 
Also, get in the habit of saving versions of your ztools or projects so you can go back to an earlier version when you have issues like this.
Sorry Jesse but this is misleading advice. Zremesher a great tool for rebuilding Sub-D levels.
Duplicate your subtool and Zremesh it to about 10-20K(or for more accurate results you can divide your highest level face-count by four as many times as it takes and this will give you the facecount needed for your Zremesh and the amount of levels to divide it by)
So for instance if your highest level is 2.7 million then :
2.7 / 4= 675.000 / 4=168,750 / 4=42,188 / 4=10,545
So Zremesh to 11,000 and divide it 4 times so the new mesh is slightly more than the original.
Now you just ‘project all’ on the lowest level and repeat as you step up through each level.
This will result in a mesh with cleaner topology, subdivision levels, and your original detail.
Also, that bad GEO in your image looks like it was the thin GEO that sometimes gets leftover from clipping errors, that was then dynameshed. You can use the ‘Trim Curve’ brush instead. This will slice/trim/close holes all in one go.
Also, it’s very bad practice to sculpt on very high-poly single-level meshes before you’ve established any proper forms. It might even be a good idea to throw the sculpt out and start again at a low-poly base and gradually build up the forms. This is the most vital stage with organic sculpting and shouldn’t be rushed.
That’s an extremely useful macro. I must try it out. Thanks.
Although I still think it a lot more beneficial for the OP to learn and understand the manual process first.