There are many paint strippers available. For safety, I suggest Citristrip. Check out their web site for more info at http://www.Citristrip.com.
The more powerful strippers are methyl cloride based and, while stripping outdoor concrete would seem to be a fairly safe usage for the methyl chloride strippers, you still can have problems with the residue. And I do agree that with some of the paints that could be on concrete stairs methyl chloride based strippers may be about the only solution, I would sure try the Citristrip first. Follow the manufacturers instructions and safety precautions exactly with any of these products. They can be really dangerous.
A 20 year old house as a 2 step front entrance, walk to cement step to cement porch. The cement step is in good shape but has settled several inches leaving a higher than normal step to the porch level. Would appreciate your suggestions on correcting this without removing the step and remaking it. Is there a metal tread which could be added? Would one layer of bricks on the step hold in place? Your suggestion appreciated. Thank you for your opinion. Bill Rumbolz