I'm trouble in it... software were installed but don't know how to remove it this moment...
I'm using Debian sarge.

The easiest way would be using Synaptic (K menu->System->Synaptic package manager). This way you get a GUI. If you're ok with the command line use 'apt-get remove package_name'.
Be careful though what you remove. Synaptic will tell you if the selected package will automatically remove other ones. So, if you're not sure better leave it there.

I just find a KPackage. and i want to remove a firefox its directory is /root/firefox-installer. i don't know how to remove firefox on KPackage and apt-get remove xxx. (apt-get remove firefox-installer, don't work)

In this case 'apt-get remove' won't work (nor will KPackage) because firefox-installer is not a deb package. You probably downloaded it from somewhere via http or ftp. To remove it you must manually delete it (unless it doesn't have a uninstall program, which I doubt). For that use the 'rm' command.

BTW, why would you remove firefox? Or is it only the installer you want removed?

I just wanna try how to remove at sarge.

may anyone tell me how to remove software from shell by using commands?

Ehh...what exactly does that mean? Removing something (a file, directory, etc.) isn't distro specific.Told ya in my previous post: use the 'rm' command for individual files, like 'rm file1 file2 file3'. For directories you have at least two options: 'rm -rf /path/to/directory/directory_name' or, using two succesive commands: 'rm /directory/*' followed by 'rmdir directory'.

You should take care when specifing the path as there can be 'absolute paths', (the ones that begin with '/' and are ment to be searched beginning from the root directory) and 'relative paths' (which don't have a leading '/' and are ment to be found within the current directory).