Go to the mage and swipe left right on your screen. Select the equipment to transmute. You will see a button toward the bottom of your screen push that and hold it till the blue line makes a complete circle and your done
Probably want to fully enchant before you transmute as well because you can't enchant it once it becomes a Charm and a fully enchanted Charm has higher stats and a dope af gold border.
If you want people to enchant all this crap you give from events please boost the aqua and inferno rewards.
Thats what I was thinking. There's no way the average person has enough aqua orinferno to even come close to upgrading equip that far.