If you didn't have any Insurance in place at the time you booked the holiday, then you don't really have much choice when you arrange cover. The condition has to be disclosed, even if the mole is removed. The Insurers who will cover the condition will charge a much higher premium. Some Insurers won't offer any cover related to the condition.
You need to do some phoning around with the information to see what cover is available and at what cost.
I would suggest using a specialist Travel Insurance broker.
Eg. World-first.co.uk, Direct-travel.co.uk, allcleartravel.co.uk, freedominsure.co.uk