Not sure if the issue you describe is caused by those entries, but here is how to revert them:
Open a terminal and type the following command:
pkexec env DISPLAY=$DISPLAY XAUTHORITY=$XAUTHORITY gedit /etc/fstab
(best copy the command and paste it into the command line by pressing CTRL+SHIFT+V). You will be asked for your password.
This will open the file /etc/fstab in a text editor.
Be very careful in the editor, you are running it as root
At the end of the file you will find the following lines
#cdrom 0
/dev/sr0 /media/cdrom/ auto ro,noauto,user,exec 0 0
#cdrom 1
/dev/sr0 /media/cdrom/ auto ro,noauto,user,exec 0 0
insert a # at the beginning of the two lines starting with /dev/sr0, the save the file.
Explanation of the command line
pkexec invokes the commadnd gedit /etc/fstab with root permissions (like sudo would do, but for a GUI-program)
env DISPLAY=$DISPLAY XAUTHORITY=$XAUTHORITY send the current values for DISPLAY (usually :0) and XAUTHORITY into the respective Environment variables for pkexec, thus preventing a permission problem because the display to use does not belong to root
You should not use sudo to invoke a GUI-program, that might cause the inability to log into your Desktop.