1) To remove My courses link from the Left Sidebar
Add this CSS code in Edwiser RemUI General settings >> Custom CSS section:


.site-menubar a[data-key="mycourses"] {
display: none;
}

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2) To remove Course archive link from the button part of the Left Navigation

Navigate to Site adminstration >> Appearance >> Additional HTML >> Before BODY is closed
Add this code here:

<script>
document.querySelector(".site-menubar-footer a .fa-archive").parentElement.style.display="none";
</script>

Now navigate to Edwiser RemUI general settings >> Custom CSS section:

.site-menubar-unfold .site-menubar-footer .col-3 {
width: 33.33% !important;
max-width: 33.33% !important;
}
.site-menubar-unfold .site-menubar-footer .w-p50 {
width: 100% !important;
max-width: 100% !important;
}