resign, reassign, re-sign

Resign or resign ( z sound ) means to give up a position or job--
He threatened to resign if he didn't get a raise in salary.
The officer wanted to resign his commission, but he had no civilian job prospects.
Resign also means to submit without resistance, in a mental way--
He'll just have to resign himself to the fact that she's gone.

Reassign or reassign means to appoint to a specific duty or post ( assign ), again or anew ( re-)--
He thinks they will reassign him to an overseas post.
If they agree to reassign him, he'll be working closer to home.
Reassign or reassign may also mean allocate or allot ( assign ), again or anew ( re-)--
I hope the clerk can reassign the rooms; we were promised a view.

Re-sign or re-sign ( s sound ) means to write one's name ( sign ) again ( re-), thereby agreeing to the terms and conditions of a contract--
We have altered the contract; you'll need to re-sign where indicated.
Now read the terms and conditions and re-sign the form.

Now that you know that, you can say--
"He won't re-sign with us unless we reassign him, otherwise he'll resign."