What is the best way to remove pet odor from concrete?
Let me save you some time.  Forget the pet store products, just go to Home Depot or Lowe's and get yourself a can of primer/sealer, I think Kilz brand is the best.

I had a really bad cat urine odor problem in my townhome many years ago (from previous owners).  Like you, I went to the Internet and I tried a lot of suggestions I found there.  NONE of those specialty pet odor removal products worked.  They just temporarily covered up the smell and during hot weather it came back.  Big waste of money and time.

Finally someone suggested the Kilz brand primer/sealer and it worked.  The smell never ever came back, and there was a clean "new home" smell.  I used it on drywall but I'm sure they have stuff for concrete as well.