I've stabbed the aptaisia with a red hot scalpel several times until the flesh pealed away. Then with the scalpel scraped the area, rinsed, brushed and rinsed again all outside of the tank.
If I don't come back to update this thread then that method would of worked and there is no aptaisia in the tank.
Good luck. For future reference, I've had good results with using hydrogen peroxide to remove aiptasia. I've found that most corals tolerate it well at up to 40% hydrogen peroxide (3%)/60% tank water. A quick dip of 10 seconds or so is usually all it takes to turn an aiptasia anemone into a foaming pile of goo. They typically release from whatever surface they're attached to with just a little nudge. Removing them this way has been the most effective method I've ever used.
Pretty much every new coral I purchase gets a dip in Coral Rx then a quick/careful dip in the 40% peroxide/60% tank water solution, then an aggressive rinsing in tank water to remove the peroxide and stop the reaction. Even my expensive SPS frags get this treatment. I haven't lost a single coral, but you need to use good common sense about which corals will likely tolerate it well and which will not. Soft fleshy corals should not be dipped this way as many of them inflate their tissue with water very quickly (this is one of the reasons why it works so well for aiptasia). That being said, some soft corals will tolerate it at a reduced concentration of around 20% peroxide / 80% tank water.
I have observed that any critters on the coral are pretty much instantly stunned by the peroxide dip or they frantically bail out of the coral because the dip is super irritating to them.
This is effective against:
Algae (many varieties, including GHA and bryopsis)
Flatworms and other soft-bodied pests
Bacteria
Viruses
Protozoa
Crustaceans (many coral pests are in-fact crustaceans)
Aiptasia
Coral varieties I have dipped fully in ~40% solution without issue (no more than 5-10 seconds for most SPS at this concentration, but can tolerate longer dips at lower concentration):
Acros
Montis
Stylophora
Acan lord
Acan echinata
Zoas/Palys (very tolerant, I've dipped for as long as 1-2 minutes)
Chalices
Cyphastrea
Leptastrea
Leptoseris
Favia/Favites
Gonis
Alveopora
Blastos
Duncans
Pipe organ
Stylocoeniella
Platygyra
Avoid dipping these in high concentrations of peroxide solution:
Corallimorphs (all varieties)
Fleshy soft corals like xenia
Anemones of any kind (obviously)
Avoid submerging these in peroxide solution (I do however dip the base and the the flesh not immediately near the coral head):
Torches
Hammers
Octospawn
Elegance
Any coral variety I have not mentioned, I have not tried. This method isn't for the faint of heart! You have to be mindful of what coral you're dipping, what you're attempting to treat/remove and how long you subject it to the solution. And be very thorough when rinsing the coral! If you see bubbles, keep rinsing aggressively until the reaction stops, it can take 3-4 rinses and you should replace your rinse water.