I currently have a Simple IRA acct and a non-prototype 401k plan both of which are funded only by employer contributions. I've not made any employee contributions nor have I ever taken a withdrawal. I've never been married and am over 25 years away from retirement. I live in Illinois. In the next few weeks, I will be leaving my current employer and I don't want these assets to follow me. I don't want to assume ownership of these assets nor do I want these assets associated with me. How can I legally decline these assets so they're returned to my employer in full? Is there an IRS form or some kind of protocol for officially doing this? I am absolutely 100% certain this is what I want to do and I want to do it "legally and officially". I realize this may sound like an odd request but I've my reasons. Any advice?

If you are vested and the funds are yours, no, they are yours and remain yours.
If you just leave them, depending on the interest rate and depending on the annual fees, the money may be gone over years of fees I no additional money put in, Depending on the sum of money involved.

Also, if this would be an issue of someone else having a claim, and they are entinted to part of this money, if you did, find a way to just give it away, you could still be liable for it, under some fraud statues.

As a note, you take the money and donate it, then it is gone.