I have two iPhones showing on my iCloud. My old iPhone 6 and my new iPhone 13. My icloud says it cant backup because my storage is full. My old phone shows it has backed up 35Gb. Can I delete the 35 Gb from my icloud old phone using my new phone, ? I don't have the old phone as I traded it back to version when I got the new phone.
iPhone 13, iOS 15
Yes. See the following from Manage your iCloud storage - Apple Support
Delete backups and turn off iCloud Backup for your device
You can delete old iCloud backups for the device you're currently using, or older devices you may not use anymore. iCloud backups are available for 180 days after you disable or stop using iCloud Backup. Backups that are currently being used to restore a device can't be deleted.
iPhone, iPad, and iPod touch
When you delete a backup, it also turns off iCloud Backup for your iPhone, iPad, or iPod touch. You can turn iCloud Backup back on in iCloud settings on your device.
Yes. See the following from Manage your iCloud storage - Apple Support
Delete backups and turn off iCloud Backup for your device
You can delete old iCloud backups for the device you're currently using, or older devices you may not use anymore. iCloud backups are available for 180 days after you disable or stop using iCloud Backup. Backups that are currently being used to restore a device can't be deleted.
iPhone, iPad, and iPod touch
When you delete a backup, it also turns off iCloud Backup for your iPhone, iPad, or iPod touch. You can turn iCloud Backup back on in iCloud settings on your device.
I cloud backup
