If you really want to wreck your credit with a foreclosure, you just stop paying your mortgage. It's that easy. The bank will come after you soon enough.
If I were you though, I'd reach out to a real estate agent and find out if you can sell your house for enough to at least break even. If your home just appraised for enough for you to cash out that much equity, perhaps you can sell it, save your credit and move elsewhere. If you price it right, you can sell faster than your lender would foreclose.