Sign in and pick up where you left off.
Every story keeps its own chapters and its own story bible. Nothing is ever deleted.
It reads all of this every time, before it writes anything. When a chapter finishes it adds what the chapter established — it can only ever add. You can change or delete any line, and it will believe you.
It reads this every time, before it writes anything. Change a line, then try it out below and see what it does.
The old one is always kept, so you can go back whenever you like. Your story stays exactly as it is either way.