Black bar

That’s the WordPress Toolbar (aka Admin Bar).

Some plugins (eg BuddyPress) have a switch to turn on/off the admin bar for visitors.

If you’re not using any of these plugins, kindly switch the theme to default and see if it disappears.

If it disappears with the default theme active, chances are your Experon theme is somehow calling the admin toolbar. Ask here for help: https://www.ads-software.com/support/theme/experon

If the admin bar still shows on the default theme, then something else is calling it. See if this fixes your issue: https://www.ads-software.com/support/topic/admin-bar-shows-when-logged-out/

Thank you, I solved it with a plugin.