The “transaction costs” of selling and then renting or buying a cheaper place are huge. Commissions, fixup costs of the house, searching for a replacement, the cost of moving & downsizing possessions, school changes if you have kids–the list goes on and on, and the costs are psychic as well as monetary.
And you would be throwing away a terrific 30-year loan. By owning this house for only four years, your net worth has increased by $170,000. Let it ride and it will probably keep growing.
Instead, attack your expenses with a vengeance. Live under a budget.