Hi Gail, Kelnaven and tygb...
Thank you for being here !
On the past three days, I have been in contact to apple services about this problem, but we don't have a solution yet. I spoke with two different level assistants (the first assistant and her superior). So now, we are going to another level of assistance, engineers from apple are allowed to get into my icloud account and they are going to see deeper... More news about this will come around 20 November, so in two weeks.
I also have made some little progress with the problems I described before :
1. I understood why the folder that I was trying to erase was blocked on the saving process. This only happens when the folder that I'm trying to erase also contains subfolders. So I put all the folders at the same level, and then, Icloud was able to conclude the saving process... But after logging out and logging in from my icloud.com, the folders keep coming back.
2. The aim that I'm pursuing here since the beginning is to erase 6 folders. I have some good news, because I already erased 2 folders. But I still have 4 folders on the waiting list... The question now is: what I'm waiting for to do it? Well, this 2 folders disappear, but it is not clear how I did it. I have been following the magical step-by-step described by Gail before, that is: using two different methods (event three), many times, until the folders finally disappeared. All of this directly on Icloud.com. But this two folders did not disappear on the same day, only with a lapse of time of two days. So there is a hypothesis that icloud.com needs extra-time to process the order of erasing folders. Next days, I will be concentrating the process on one folder, and then I will tell you what I find.
3. Gail you also said that you create new folders and you make them disappear with the method you described before. So I decided to create new folders and see if I was also able to make them disappear, and it definitely works. But the ancient folders are not erasing. So there may be a difference between new folders and ancient folders... Maybe you can try creating two folders with notes inside and try to erase them after two or three days, and see if it is still working.
4. tygb, you sent me a link with instructions to erase notes. By the moment, I don't really have problems with erasing notes, but with erasing folders in which the notes are organised.
5. Kelnaven, by the moment, I will not erase my notes, but if I don't have a better solution in two weeks via apple service, I will consider this option again. Thank you for your advice !
I will be back with new discoveries about this bug. I'm still reading and following your advices. Thanks again!