Be careful. If the wrong drive is removed, the VM will no longer boot. If you are concerned, clone the VM first before proceeding.

# Power off the VM.
# <code>VirtualBox</code> &rarr; <code>click a VM</code> &rarr; <code>Settings</code> &rarr; <code>Storage</code> &rarr; <code>click on DVD device symbol</code> &rarr; <code>click on disk removal symbol</code>
# VirtualBox will ask:
<blockquote>Are you sure you want to delete the optical drive?</blockquote>
<blockquote>You will not be able to insert any optical disks or ISO images or install the Guest Additions without it!</blockquote>
4. <code>Click "Remove"</code>