I would remove the vinyl, but if it is in good shape and not releasing at any points, you may be able to go over it. I however, do not recommend it.
Removal is easy if you spend $30 for a long handled tile scraper. You can get those at any home center. They take the back and knee breaking agony from the project, however, around corners and under cabinets you will need a chisel and get on your knees for this.
Do not gouge the underlayment with these tools as you will have to re float that area.