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.