Apple - How Do I Remove Remote Disc from Finder (not in the Sidebar)

To remove:

1. Launch Terminal

2. Enter the following string:

   defaults write com.apple.NetworkBrowser EnableODiskBrowsing -bool false
   

3. Enter the following string:

   killall Finder
   

The icon should now be gone from both Finder and your sidebar. To reverse and make the icon show again, repeat the steps but run this command in step 2:

defaults delete com.apple.NetworkBrowser EnableODiskBrowsing

The icon is present on Macs which do not have optical drives but may still need access to the physical media from another computer.

Source: Apple Support Forums