https://prnt.sc/xspa3w – it is duplicated because you imported a few of demos.
Menus can be edited via Appearance > Menus.
If you want to run the fresh WordPress installation you can use WordPress Database Reset plugin https://wordpress.org/plugins/wordpress-database-reset/ The plugin can be used to remove all the existing content and install a new version from scratch. It is recommended to disable the theme https://prnt.sc/unle03 before the reset.
