If someone wants to donate a trailer to a non-profit what is the process?

I'm assuming you want the tax-write-off for a charitable donation--if you're not worried about taxes, you just need some piece of paper (either provided by them or written by yourself) which states that ownership is being transferred and it is now theirs; the paper should also note that you no longer have any responsilbility or liability for it, they will pay call costs of moving it, they take it as is, etc. However, as long as you cover all those bases, it's simple.

(Note:  you don't describe what kind of "trailer" this is--if it's one that is in some way is registered with the state, you'd need to let the state agencies know, too. And if there's any lien or financing agreement on it, that would need to be paid off.)

If you're talking about a trailer home, btw, and not something more modest, then you should get an attorney to help you, since you would also need to deal with homeowner's insurance, possibly getting deeds filed, etc. It would be reasonable to have the non-profit pick up the attorney cost, though make sure you hire him/her so they have your interest in mind.

If you want to make sure you get a tax benefit, do as above, but first make sure this is a registered charity--get their ID number and check it out with the state that this is an organization that you can get a deduction for donating to. Note that all non-profits are NOT necessarily charities that get you a tax break.

If they are a legitimate charity, then you'll need an acknowledgment and receipt from them that the got the trailer and it's value was whatever it was, for your tax records.