BLUE TONGUE SKINKS

I put sphagnum moss in my enclosure and it raised the humidity up to 80-90% I am installing a 6" cabinet fan should I pull air out or push air in to lower humidity

Depending on what sub/species of BTS you have, 80-90% humidity might actually be perfect, and with the heat in the tank, it will evaporate quickly enough. There are few skinks available in the US that would be hurt by that level of humidity for a while.
Are you talking about mounting a fan inside the tank? Or one to blow into the tank?
Unless the whole room is much the same temperature as the inside of the tank, I would think that a fan blowing in, or into, the tank in wet conditions, would do more potential harm than just leaving the humidity to evaporate on its own.

What species do you have?

Hi! Post a pic of your skink and we can help identify the species. Indonesian species need pretty high humidity anyway - some higher than others - but as long as it's air humid and not soggy wet high humidity might not be a problem. A more common problem is humidity that's too low which will cause health conditions in the long term. Post a pic of your enclosure setup too if you like .

I have a baby Northern. I have spahgnum peat moss for substrate. Someone posted that once it dried out it would be ok. I have ordered aspen shavings just in case. Between fan and dimmer it seems to be bringing it down to around 50-55%

This is Yoshi