Remove Author, Date & Comment Count in Archives/Seach Results

You could create a proper Child Theme and then edit the template used for this content or hide it with CSS. Hiding with CSS does not remove the source code. It just will not display.

For help with CSS, a live site link is required…if we cannot see the site, we cannot see the stylesheet(s), so we cannot suggest changes.

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

There are others.

When editing CSS, use a Child Theme
http://codex.wordpress.org/Child_Themes
Custom CSS Plugin, or Theme provided custom CSS option.
Edits to parent themes are lost on theme update.

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