I would turn it on without a cooler, just without the paste. that way i dont have to buy any paste remover?
Or does the stock cooler not leave paste on the chip?
The stock cooler will leave a paste residue.
Rubbing alcohol works well as a paste remover. I use paper coffee filters which are lint free.
It is wise, anyway, to be prepared to remount a cooler. You should get a tube of paste with the cooler that is good for several applications. Remember, use as little paste as possible. Too much acts as an insulator.