Pages Not Supported

Hello my problem was originally the automatic creation and without my consent of hundreds of page folder named J, which I can not delete but now I have a J [NOT TAKEN INTO ACCOUNT] which is in my main menu that is placed in the middle of my design. I have to launch the site tomorrow I do not know how to get out to delete this page I can not delete.
has anyone had this kind of problem and how can I delete it?
Sincerely Christian

I've never heard of any problems like this. What happened around this:

48 minutes ago, ChristianEclore said:

automatic creation and without my consent of hundreds of page folder named J

Can you share your website URL and some screenshots of this in your dashboard?

Is this a very recent problem? Have you spoken to Squarespace Support?

Thank you Ziggy. for your reply. 
I don't know why when I created a "Dossier" page at some point, the editor bugged and as a result I have lots of "folder" pages named J as in the following image and some of them are impossible to move and become J[NOT SUPPORTED].
As for Technical Support, they don't answer so I turned to the forum to see if anyone had already had the same problem.

site : https://www.eclore-le-jeu.fr

Apart from getting on the live chat for support, I would suggest clearing your browser cache and deleting these folders, hopefully it doesn't happen again. Errors in any injected code may also be to blame for this, do you have any custom coding added to the website?

Thanks for the help, I've started deleting folders but if I have to do it one by one it's going to take me days as there are well over a hundred of these j folders not counting those that are impossible to delete. I did inject some custom code to change a typeface, but I don't know if that's the problem, but I can delete it.

1 hour ago, ChristianEclore said:

but I can delete it.

No need to do that, but sharing it and anything you have in code injection or code blocks might help us understand what's going on.