If it isn't hogging CPU or Memory or doing anything else unwanted I'd recommend you just leave it alone. It might be safe to just end the process, or it might cause various other programs on your computer that may be dependent on it to fail, forcing you to restart. Or it could even cause system-wide destruction of your computer causing it to explode in your face. Or something similar
According to this page What is LANMAN WORKSTATION in my services in task manager? - Yahoo! Answers
you really don't want to mess with it, it seems to me like it's a required service for networking (anything that involves an internet connection). So if it's causing problems let us know and we'll see what can be done about it, but I'd recommend you leave it alone otherwise.