Had the exact same issue, couldn't get rid of the "untitled dvd" option in the sidebar window of every Finder window.
Open the Disk Utility Application, select your CD/DVD Rom Drive
Choose the Yellow & black BURN option. It should open up a window asking "Select Image to Burn"
Instead of choosing a folder - simply select the "Untitled DVD" option in the sidebar and drag and drop it elsewhere. You should see it "poof" disappear.
Worked for me, hope this helps someone else.
Open the Disk Utility Application, select your CD/DVD Rom Drive
Choose the Yellow & black BURN option. It should open up a window asking "Select Image to Burn"
Instead of choosing a folder - simply select the "Untitled DVD" option in the sidebar and drag and drop it elsewhere. You should see it "poof" disappear.
Worked for me, hope this helps someone else.