Removing Augments
Removing augments is easy to do however one thing to note is it does cost 50,000 entropy to remove augments.
Removing augments can be useful for a number of reasons but the main one would be to change the augments to a different rod.
1. Place the fishing rod with the augments you want to remove in to the same slot that you placed it to add them as pictured bellow. This is the menu you accessed with the /fish augment command.

/fish augment GUI
2. Next click on the TNT block marked "Remove Augments". All of the augments that were on your rod should now appear in your inventory.