Removing carbon when dosing meds is an urban myth. Removing FRESH carbon when dosing meds is what should be said. After a certain amount of time which is argued about by many people the carbon is 'exhausted'.
Carbon adsorbs not absorbs so things 'stick' to it rather than being soaked up by it, therefore once it has been covered it is exhausted. It can be recharged apparently by baking at 500F.
The times stated for it 'adsorbtion life' are between 24 hours and 1 month but noone agrees
After the carbon is exhausted then it becomes standard biomedia so theres no point taking it out for any reason really.
I have charcoal in my filter permanently as it has very good surface area
The question should be more of should I add carbon rather than should I remove it. If it is already in there then leave it as it is most probably just biomedia now. It it isn't then don't add it.
AC