Thanks for the reply.
Please delete this custom css code – http://prntscr.com/obokc7 to remove mentioned borders (this demo version was created before the adding new settings for the menu, so borders were added using custom code).
5.4 version of the theme has a bug with “Border width” in Theme Options > Menu > Menu styling > Main menu links. After the next update, you will be able to add borders for menu items via Theme Options.
Be attentive, use only Private content area to post private information like access to your Dashboard http://prntscr.com/nwlnrv