If you want to be silly, sell them on a exchange, like binance or something.
Binance.com only allows you to cash out to stablecoins, which very likely isn't what OP is looking for, and not something I would recommend people to do. Binance.je allows you to cash out to actual fiat in form of EUR and GBP, but not to other fiat currencies.
Now you are set! Send the BTC to the exchange, sell it, withdraw the fiat currency to your bank.
It's probably useful to add that exchanges do require KYC, which means that you have to submit all your personal information, scans of ID, utility bills, etc. It also means that an exchange and very likely your local IRS has enough data to hold you accountable in case you do not pay your taxes, so think carefully before you verify yourself and send your coins over to cash out.
Most reputable exchanges; Coinbase, Bitstamp, Kraken and Gemini.