Right way to do this is by going to Appearance > Customize > Additional CSS and putting the following CSS code there:
a.enigma_scrollup {display: none !important;}
Usually you should not use !important but inspection of your page shows that the style for “Go Top” button is written inline (display: block;), i.e.
<a href="#" title="Go Top" class="enigma_scrollup" style="display: block;"><i class="fa fa-chevron-up"></i></a>. So in order to override this rule you need an !important to be imposed from outside.
If the above does not work try the following:
Locate which file in your theme the above markup is placed and change display:block; to display:none;.
Hope this helps.
You are welcome. Can you please mark your question as Resolved? 🙂
