.scheme_original .menu_main_nav > li#blob { display: none; }

Or specifically from the donate button:

.menu_main_nav .donate > #blob { display: none; }

You’ll have to add on your own donate hover though:

.menu_main_nav > li.blob_over.donate:not(.current-menu-item):not(.current-menu-parent):not(.current-menu-ancestor):hover { background-color: #981fe9; }