this error is coming on the very first command in setting bolt python library in vmware i.e. sudo apt-get -y update
To resolve this problem from terminal you must remove/comment this CD-ROM repository source directly from
sudo nano /etc/apt/sources.list
and comment or remove lines that include cdrom . eg:
deb cdrom:[Ubuntu-Server 16.04 LTS _Xenial Xerus_ - Release amd64 (20160420.3)]/ xenial main restricted
Do let me know in case you need any other information.