erase rewritable cd - disc utility el capitan

Using Finder to erase a CD works well provided that the cd can be mounted. I configured my mac to "ignore" when inserting a music cd (via System Preferences-> CDs & DVDs) and iTunes is not running, inserting a music cd (RW) will be mounted and visible from Finder to erase.

However, if iTunes is running, inserting the music cd will be mounted and opened in iTunes (overriding the "ignore" preference). In this scenario, I have to quit iTunes and then I can erase the music cd.

And I've also encountered the situation where iTunes had encountered an error while writing to a cd. In my case the cd was merely dirty. After cleaning the cd, I can't erase the cd because it cannot be mounted (using Finder or df from Terminal). However, it's "visible" from Disk Utility; and I can see the greyed out mount name -- but it cannot be erased (nor repaired, etc).

Thank you!!!!