I guess you've to reconsider the Unlikeable battery icon in theI wrote to LG yesterday. I just received the response.
The battery icon cannot be removed as it part of the update to Android 7.0, Nougat.
To remove the message about slow charging, they suggest a factory reset as a possible workaround. Is this a cure? They don't say for sure.
I am not pleased. I'm not interested in starting over again.