Turn off icloud notification to increase storage without turning off back-up

Im using iCloud as a back-up but my storage is full. I want to disable the notification which says: "Your iCloud storage is full. You can remove files from iCloud or purchase additional space. "

I do not want to remove files or purchase additional space. I just want to maintain the currently backed-up files.

However while using Notes I get the notification above every few minutes and it is driving me crazy. I have to click cancel every time to continue in my note.

The same problem occurs in my iPad.