Hello
Yes it is possible
Go to dashboard > appearance > customize > additional css
Copy the code given below and paste it in the additional css text-box

.ht-slide-cap-title.animated.fadeInDown {
background-color: transparent;
}
.ht-slide-cap-desc {
background-color: transparent;
}

Then click on publish

Note: If you change the background color of the title / caption to transparent then you also might need to change the title color as well. This option is available in customizer already.
Goto dashboard > appearance > customize > home section > slider section
You will see the color options there.

Thank you