How to hide the line numbers in Notepad++

If you download the latest version (5.7?), the Run Menu has four different "Launch in browser" menu items (IE, Firefox, Chrome, and Safari)

I've only just looked at a reference sheet, so there's probably a better way to do this, but you could do something like this with the Replace dialog (Ctrl+H):

Find: ([0-9a-zA-Z]*)([0-9a-zA-Z ]*$)
Replace: \1

The way I read it is basically:
[0-9a-zA-Z] : match an alphanumeric character
* : keep matching them
[0-9a-zA-Z ] : match an alphanumeric character or a space
$ : match the end of the line
() : "holds" a match in a variable. The first () holds a match in \1, the second in \2 (which we don't need).

Since the first () is "holding" the match you want, that will be what you are replacing the text with. It does this for each line if you hit Replace All.