Thank you.
Actually… killing a couple of birds with one stone:
Single up and down level buttons.
That could be really handy if you’re desperate for some ISO8 for levelling up a better covered character! I’m very much liking that one! 
If they did that, everyone would just shift their ISO into whichever characters they’re about to use, and every battle would be between maxed characters.
They could mitigate that somewhat by having it come back out at a loss. Say you level a character down and get 1/3 of the ISO back.
I’m not a huge fan of the deleveling idea, but this could be one way to allow it and keep it from being a constantly re-usable pool.
Everyone above makes really good points.
I hadn’t gone into any specific details (which the devs would do anyway) but yes, so as to make it a useful tool but not halt ISO sales, you would just return X% of the initially used amount.
I wouldn’t ask for any ISO back if I was able to de-level, I would actually pay ISO to be able to de-level.
I think you guys are asking for too much… Lets be realistic! Just let us de-level and loose the ISO invested! It would still be incredibly useful AND it wouldnt affect ISO sales… PLEASE make this happen, you guys know that softcaping can be a huge part of this game!
How about un-covering? For the people that mistakenly added more than 2covers to IM40’s yellow.