This is possible on different ways. You can remove the enchantment and keeping the old item in Minecraft Dungeons .  Let the Blacksmith upgrade an item for you. This give you back the points. The Weapon/Armor will be not destoyed. If did not unlock the Blackshmit yet: You can unlock the Blacksmith in “Creeper Woods”. You can destroy and item to get the points back. Maybe the Entchantsmith have an option to get back the points but I'm not sure about it. I hope this will help you.