This feature is present on many private server and mostly the NPC location is the same
first go to the Prontera forge at the center square of Prontera
in the forge go to the left portal there you will see a npc by the desk name old wise women.
talk to her she will tell you she has the power to remove card from equipments.
She will charge a base zeny of 200,000 plus 25000z each card in the equipment.
She will additionally need 1 yellow gemstone and 1 star crumb each equipment you bring to her.
there are 90% success chances and if failed nothing is lost!