can you delete previous back ups

Are you referring to iCloud backups? If YES, then there is only one backup on iCloud for your iPhone. iCloud backs up your iPhone approximately once every 24 hours and is a continuously updated file.

You may have backups from previously owned devices with the same Apple ID and you can delete those backups by locating them in iCloud. Open Settings ➔ Apple ID (Your Name at Top) ➔ iCloud ➔ Manage Storage ➔ Backups: Here, you can select the backups from all your devices and then delete the backup(s). Ensure that you do not accidentally delete your current device's backup file.

Axel F.