Well, I sent that discord message immediately after I made the bank transfer.
At the time of writing this it's now been almost 5 days and it still refuses to let me delete my nation. I'm not in any alliance anymore.
Edit: Nevermind. It finally deleted my nation.
It has been way past 3 days now, yet it is stull telling me I need to wait in order to delete my nation. Discord screenshot is of when I made the last bank deposit, which was 4 days ago now.