As a reseller, where do I enter in merchandise I returned to the original store on my taxes?

You will subtract the cost of your returned purchases from the amount of Purchases on your tax return.

Thank you, so it doesn't go in it's own separate box, like the cost of goods withdrawn for personal use?

For example, if I bought 10 pairs of shoes that cost $100 each, and I sold 7 pairs, kept 1 pair for myself, and returned 2 pairs, I would put $700 for the cost of goods and $100 for the cost of goods withdrawn for personal use? The value of the 2 returned pairs wouldn't be accounted for in a separate box?

No, as MihnT1 said, you would subtract the pairs you returned from purchases. You would account for the pair that you took for yourself as withdrawn for personal use.