I removed a tub unit in a house.I built a shower in its place,the ptrap from the tub was removed and my worker forgot to put one back.The shower has a cement pan in,and its tiled,the customer says there is a smell from the drain.There is no access panel under the cabinet,is there anything that I can put to get rid of the smell?This is in a concrete floor,or should I tear out the shower floor?

You have no choice in this matter. Your worker, he couldn't be a plumber that did this, lef your customer with a direct open connection between the city sewer and his house. That's where the bad smell comes from. Tear the shower base out and do the job right by code. And be very glad the customer don't sue the pants off you for creating and then leaving a hazrdous situation inhis home. Good luck, Tom