Hi...It is not needed to remove vinyl flooring you can cover with cement board if your setting material is thinset or you can use plywood with a paste adhesive to set your tile...Again I do not recommend removing vinyl floor it may have been installed after 1975 but wo knows how long it sat in a warehouse..its not worth taking the chance
check with your tile supplier there is a adhesive you can use to set tileright on top of the vinyl...just do somemore research to find which method is best for you good luck