Removing two lines from the bottom of the site

With this CSS is the easiest way without modifying the theme files

.author-credit, .site-info {display: none;}

You can then review the forced height on the footer and maybe use:

#colophon {min-height: 50px;}

To discover what CSS is output by your theme, use a web inspection tool such as Firebug: https://getfirebug.com/ , Chrome Inspect Element: https://developers.google.com/chrome-developer-tools/ or Internet Explorer 9+ F12 Dev. Tools: https://msdn.microsoft.com/en-us/library/dd565627(v=vs.85).aspx#csstool

There are others.

When editing CSS, use a Child Theme
https://codex.www.ads-software.com/Child_Themes
Custom CSS Plugin, or Theme provided custom CSS option.
Edits to parent themes are lost on theme update.

Learn CSS: https://www.w3schools.com/css/

Go to your WordPress site admin panel.
-> Under Appearance click on Editor.
-> In style.css write this code at bottom.

.site-info,.author-credit { display: none; }

Update file and your are done.

->if you are familier with code then you can edit in footer.php file too.