Cannot remove custom menu item from main menu

I took over our club website as admin recently. The website has been inactive for a long time. Even the club name has been changed now. There is a menu item in the main menu with the old club name. It directs to a "site can’t be reached". I want to update this menu item text and link or remove it. I don't find an option to do this. How can I do this?

Website URL - dialog.toastmastersclubs.org/

The below highlighted menu item has to be updated/ removed.

Please read the documentation on custom pages and links
support.toastmastersclubs.org/doc/item/links-to-other-sites