If you mean to hide the bars of the first slider, you could add the property in your stylesheet:
.carousel-indicators{
display:none !important;
}
It's a big question, look, I'll explain how this works.
The z-index of your image does not work in relation to the z-index of the OL because although the number is greater, the image is inside a parent div that is not the same as the parent of the OL.
So z-index always works in relation to the father.
A code example of what I speak is this:
<div class="padre1" style="z-index: 1">
<div class="hijo1" style="z-index: 10000"></div>
</div>
<div class="padre2" style="z-index: 2">
<div class="hijo2" style="z-index: 0"></div>
</div>
In this case that I present to you, the "hijo1" will be below the "hijo2" because they are "prisoners" of their corresponding parents.
Bearing that in mind, I recommend you reformulate the structure of your HTML to try to have the OL and the image under the same parent and in that way play with them until you achieve what you want.
I send you a greeting and I hope I helped you with my turns explaining something.