Type on two lists

If a type instance is on two lists do you have to remove it from both to delete it?

Yes.

thanks, i think im getting the hang of it now,

to free an image or sound i have to remove all variables that point to it right?

or let them go out of scope.

... so yes. :)
Remove them from lists. For all other variables and arrays (Global ones) just set them to null.
Local variables inside functions/methods can safely be ignored if you should want to. Since as soon as the function/method returns it will go out of scope and any local varaible will be freed.

ok thanks for the explanation