Hey there dakufromedmonton,
Thanks for reaching out to Apple Support Communities. I understand you’re having issues deleting an iCloud backup. I’ll be happy to help with this.
Do you have a computer you can use to delete the backup? If so, follow the steps in this link:
Remove a device backup from iCloud
If you don’t have a device you can use, go to Settings > Your Name and Sign Out of your account. Restart your iPhone once that is complete:
Restart your iPhone, iPad, or iPod touch
Sign back in once the restart is complete and try removing the backup once more.
Let us know if this helps
Cheers.