Buy a solvent for the appropriate slot from the magus NPC in one of the camps, and combine with the augmented item in the same type of container you used to create it. It will return the original item, but will destroy the augment gem.
Augmentations are a new feature to Everquest added with the Lost Dungeons of Norrath expansion. Basically you can fuse them to gear that you already own, enhancing the gear. In this case, adding an Exquisite Emerald of Poison Protection will increase the PR-rating of the item it is fused with by +5.
From what I hae seen and heard, the following rules cover how Augmentations can be used:
1. Armor will have a set number of "slots" for augmentations to be added to.
2. Augmentations are split out by types. If an augmentation is listed as "Type 2", it can only be fused with a piece of gear with an open "Type 2" slot. This particular augmentation can go into any type of augmentation slot.
3. Many augmentations are limited as to the inventory slots they will work in. I'm going to assume this means they cannot be added to items that are placed in other slots (I've only gotten the augment you earn for talking to the Wayfarers to activate LDoN, and fused it to my PoP charm without even trying to see if I could fuse it to another piece of gear that it "shouldn't" work with)
4. Equipment that is normally tradable becomes NO DROP while it is augmented. This leads to the last rule:
5. An augmentation can be removed from a piece of equipment, but doing so will destroy it. Removing an augment simply serves to free up that Augmentation slot, either to allow you to add a better augment or to make the equipment tradable again (assuming it was not NO DROP before it was augmented).
To fuse an Augmentation to a piece of gear, go to one of the wayfarer camps and look for one of the "bird baths". Click on it and a 2-slot window will open. Place the augmentation and the piece of equipment to be augmented in it and click Combine to fuse them.
The Magus in each camp sells solvents. You need to purchase the solvent which matches the slot you wish to free up. Combine the solvent and the augmented item in the bird bath and the slot will be available.