I work in a union I've put into 401k for a while now but now I need to take a portion of it out but I don't really know who my plan administrator is so I do that. How do I find this out?

Contact information should be provided on your quarterly statement. If you have on-line access to your account you should be able to find a "Contact Us" web page. If that doesn't work, call your HR depatrment and ask who to contact.

Something to consider: think about the possibility of taking a loan against your 401(k) as opposed to an outright withdrawal. If you are under 59-1/2 years of age a loan can be a substantially better option.