Found my old Bitcoin Address/Private Key with a balance

Hi all, I've used to buy and sell bitcoins in NYC when I used to be a teen (16 years old) during the time of casascius coins/bars in physical form.

So today I was going through an old hard drive with some bitcoin files both public/private key that I've kept archived and upon running through all of them, I've discovered one of them still has a balance on it –at the time I do recall leaving as is now due to the low denomination at the time.

Given it's been a while since I used to transact with crypto (a decade and years), how would I go about converting this to cash or reinvesting it on a wallet? At the time I'd use BTC-E or Mt Gox, not sure what the deal is these days (i.e putting it on Robbin Hood, Coinbase, etc).