I am currently using Kali OS (based on debian). When I insert a dvd or usb, it automatically mounts and opens. Is it advisable to not keep automount option in linux as we are suggested in windows. What all harms can be done in case of linux with automount option ? Can anyone tell from where to disable this feature?
You confuse automount with autorun.
Automount is basically not harmfull as it only connects the device with your computer. This is also done in Windows (when the drive letter occurs it is mounted automatically). In Windows automount is activated always (without hacks it cannot be deactivated) where in Linux you have an easy choice.
What is dangerous is autorun. This is dangerous on Windows and on Linux as it can run unwanted scripts. Therefore I would suggest to turn it off.