Unable to remove space below footer

Looks like this CSS rule controls it:

.modal-content {
    height: 490px;
}

Make that height zero.

Don’t edit the theme files directly, otherwise your changes will be overwritten whenever the theme is updated.

A custom CSS editor (usually titled Additional CSS) is included in the Customizer as of WordPress 4.7 specifically for this purpose.

As an alternative, especially if you intend to modify more than just CSS, create a child theme.

I could locate Additional CSS but unable to access the file that contains the above-mentioned code (or rather any code) to edit.

.modal-content {
height: 490px;
}

What I find is a facility to add only new codes.

The issue is resolved after adding a new plugin SiteOrigin CSS and pasting the above-mentioned code:

.modal-content {
height: 0;
}

Maybe, I could have achieved the same result from the Additional CSS where there is a facility to add new codes.
However, I still want to know an easy way to read already written CSS file code.

Below footer, there is text Cart, Close showing which is not needed and not sure how it appeared.

I recommend asking at https://www.ads-software.com/support/theme/hitmag so the theme’s developers and support community can help you with this.