The part surrounding the jacks is a thick sticker. The tip of a hobby knife is the easiest way to lift the sticker. However, it is very likely to cause small scratches in the surrounding area. A small piece of tape beneath the blade can help protect the paint somewhat.

Once there is enough room, insert a plastic tool like a spudger or guitar pick to prevent further damage.

Gently pry the sticker so that the 3.5mm jack end can be lifted.

While fairly robust, the sticker can crease if bent too far. Try to keep the angle less than 45 degrees.