We can’t set up your website for you as part of our theme support so you are going to need to look for yourself.
Background images can be set in various places. First check all the demo headers. To check a header go to the layout manager (Appearance > Layouts) and in the table under the “Headers” heading click on a header’s name to review the settings for that header. On the header settings page look to see if an image URL is in the Background image input box under the “Page Background Options” heading. For example…
Check every header and remove any references to the para.llel.us domain.
Next check all the demo slideshows. Go to Appearance > Slide Shows and click on a slideshow’s name to review its settings. If the Slide show type option is set to “Background slider” then edit each slide and remove any references to the para.llel.us domain. For example…
I can’t do this work for you.