I've always wondered this. Even if you have $10k USD worth of BTC, you still need to find someone to buy it? What if you wanted to cash out $100k or $500k? At that point you need legal contracts, escrows, 3rd party verification, etc..
Actually I don't think any wallet will let you do that. How ever, you can install breadwallet on another phone/device (don't mess with your existing one) and restore with your backup seed (12 or 24 words one). Electrum is another good wallet for desktop that supports all kinds of seed words where you can again import your seed words and re-spend them. The newly installed wallets will let you spend it again because it has no way of knowing that you already spent it.