How to remove a third party software that is installed but cannot be located?

Try thissudo apt-get autoremove nero you may have to replace "nero" with the correct package name.

OR You can try synaptic package manager sudo apt-get install synaptic start it from dash an search "nero"

Good luck

This should find it if it is a package in the apt manager

$ apt-cache showpkg *nero*

You could do a search for it as well

$ locate nero

if you want to see where is is running the binary you can try

$ which nero

If its running a process somewhere you can find the process with

$ ps aux | grep 'nero'

Just delete the binary "/usr/bin/nero" it has no install package so cannot be uninstalled with apt