How you say goodbye shapes the memory of the entire conversation. A great chat with a bad ending feels worse than a mediocre chat with a warm close.
Don't just disappear.
Ghosting out mid-conversation — even on anonymous chat — leaves the other person hanging. A simple 'I've got to go now' is enough to close with respect.
Say the real thing.
If the conversation was good, say so. 'This was genuinely fun' or 'I really enjoyed talking to you' costs nothing and means everything.
Leave a door open if you mean it.
If you'd chat with this person again, say that. If you wouldn't, a warm but final goodbye is still perfectly fine. Just be honest.
The goodbye is your last impression.
End like you mean it. Warmly, honestly, and without trailing off. A good goodbye is a gift to both of you.