The #Firestorm → AO folder is protected; this means it cannot be deleted, nor can items in it be removed.
If you have inadvertently dragged something into this folder (or a subfolder), then proceed as follows:
If you had a functioning FS AO and it is now empty, it is possible that the #Firestorm → #AO folder has accidentally moved to another location.
To find the moved #AO folder, do an inventory search either for “#AO” (probably the simplest way), or in case that doesn't work, for one of the known animation names. The search will reveal both the original animation and any link to it. The link should reveal the location of the moved #AO folder. Check to see that the moved folder contains all the expected subfolders and animations.
To fix this:
First delete the new, empty folder as follows:
Now move the full #AO folder back into the correct location as follows: