I learned this trick from a very knowledgeable member here...
For the odd one I have had, I used a regular syringe with a long tube ( like airline tubing )
And about 3-5 ml of white vinegar, put the end of the tube up to mouth of the polyp, and slowly press the plunger - Aptasia gone, no fish or coral hurt.
Good for when you first catch it but probably moot if you already have a major breakout.
Just my 0.02 $ bud.