[Solved] Delete the last part of the menu [closed]

Since you haven’t included any proper code and the website link which you’ve included opens up a coming soon page, I am not quite sure what you’re referring to but from what I understand, you’d like to remove the last <li> present inside your menu. If yes, you can do that by setting the display property of the last <li> to none using the last-child psuedo-selector like this:

ul#top-menu li:last-child {
     display: none;
}

UPDATE:

Since you’ve clarified that you want to remove the background image from the last <li>, you may use this CSS:

ul#top-menu li:last-child {
     background: none;
}

If you want a solution which would work for older versions of IE then what you can do is that you can define a class for the last menu item by logging into your WordPress Dashboard, navigating to Appearance>Menus, clicking on the screen options button in the top-right corner and placing a check on CSS classes. Next, scroll down, click to open the last menu item and type the class-name inside the CSS Classes (optional) input field. After saving the menu, you can set the background to none for the last menu item by targeting the CSS class which you set for it, like this (I’ve assumed the class-name of the last menu item to be last-menu-item):

ul#top-menu li.last-menu-item {
     background: none;
}