Some accounts show assets in reserve because there are open orders in the market. This includes partially filled orders.
If you cancel all orders and there's still a small amount held in reserve, that's probably just rounding error from paritally filled orders that were cancelled.
In most cases this reserve amount shouldn't be worth more than a penny or so, but if larger amounts are stuck in reserve, contact support@ionomy.com or use this support form:
RE: Ionomy; CMC; Witness Votes