Can I flag for deletion? I upload this one by mistake
You don't need to worry about it. If no one approves it within three days, it will be deleted automatically.
Manual deletion is only done if the post is of exceptionally poor quality or breaks the rules in some other way. In those cases, the deleted upload will take up five of your upload slots until three days have passed, so you'll be better off if it stays pending for those three days instead.
"Do you know who I am? I'm the smol vtuber who's gonna burn your house down! With the lemons! I'm gonna get my manager-sans to invent a combustible lemon that burns your house down!"