Hello simbater,
Thank you for using Reef Theme. You can do it by adding custom CSS from appearance > customize > additional CSS section.
Add your CSS just like this:
.main-navigation .current_page_item > a:before, .main-navigation .current-menu-item > a:before, .main-navigation .current_page_ancestor > a:before, .main-navigation .current-menu-ancestor > a:before, .main-navigation li:hover > a:before { display: none; }
OR by customizing the theme. If you are planning to customize the theme, we always recommend to create a child theme and customize it.
Please check the following reference link to create the child theme.
https://codex.wordpress.org/Child_Themes
Hope it will help you.
Thanks,
Keon Themes Support Team