Add this CSS code in Edwiser RemUI general settings >> Custom CSS section:

While using Edwiser Course format in the course:
#page-course-view-remuiformat .site-menu-item a[data-key="grades"] {
display:none;
}
#page-course-view-remuiformat .site-menu-item a[data-key="participants"] {
display:none;
}

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While using other Course format in the course:
#page-course-view-topics .site-menu-item a[data-key="grades"] {
display:none;
}
#page-course-view-topics .site-menu-item a[data-key="participants"] {
display:none;
}