Annoying, isn't it? They do that a lot.
Then I come along with my disclaimer: I am not a lawyer, I don't give legal advice, I just make helpful comments. If you act on my comments, you do so at your own risk.
I found the following on the Maricopa County website.
Combining or Splitting Property / Parcels | Maricopa County, AZ
Which leads me to conclude that separate quitclaim deeds should suffice, from you as grantor to yourself as grantee. Each deed would show the new legal description of each lot. Record them and send certified copies to the county assessor.
An internet search yielded the following quitclaim deed sample that might suit your purposes.
Quit Claim Deed (deedforms.org)
See, no legal advice there. Just stuff that anybody can find with an internet search.
That being said, you would be wise to spend a few hundred for an attorney to draw up the appropriate documents. The few $$ you spend now could prevent $$$$$$$$$$$$$$ spent later.