Lets a sender delete an existing stream to a receiver
//load the token you'd like to use like this
//note that tokens may be loaded by symbol or by address
const daix = await sf.loadSuperToken("DAIx");
let flowOp = daix.deleteFlow({
sender: string,
receiver: string,
userData?: string
});
await flowOp.exec( <<ethers signer>> ); // should have same address as sender
