I painted over a gloss oil paint with a latex primer,a stairway wall that is constantly used, on the advice of the paint store. After it dried it would come off with my finger nails. I now want to remove the latex primer and paint with oil. How can I remove the latex or what else can you suggest. Thank you.

Unfortunately you have a job ahead of you. Either start sanding or use a stripper. Peeling primer is usually caused by insufficient surface prep. How did you prepare for primer?