Footer Credit

Looking at your site, you use fairy theme.

I recommend asking at https://www.ads-software.com/support/theme/fairy/#new-post so its developers and support community can help you with this

This CSS gets rid of that entire line.

.site-info.text-center {
    display: none;
}

To add or override CSS: use the “Additional CSS” option in the customizer.? https://codex.www.ads-software.com/CSS#Custom_CSS_in_WordPress or at [site]/wp-admin/customize.php if you don’t have that menu option.

Use the Chrome Developer Tools or Firefox Developer Tools to help you see and test changes to your CSS.