Roborumble Bot Details Gives Server Error
That's a longstanding-ish normal thing. IIRC, to keep clients from fighting over removing/readding bots, I think the server doesn't remove bots until a certain amount of time since the last upload for that bot.
LiteRumble doesn't do that, the moment a client requests a bot to be removed it removes it. However, it keeps all the pairing data against it for 365 days in case it is re-added so that battles don't have to be re-run.
I'm guessing the delay was due to a client taking a while to re-download the participants page.