1. Manually delete data from the account.
2. Set a retention policy on the Online Backup and Recovery Manager
3. Use the cleanup tool to mass remove data from a backup account
How to remove backed up devices, files, or files from the cloud?
A retention policy can be set to automatically delete data from the cloud-based on certain conditions to manage the space in the cloud.
Refer to the following article for steps on how to set a retention policy on the Online Backup and Recovery Manager
How to set up a retention policy in the Online Backup and Recovery Manager
The account cleanup tool can be used as a option to mass delete data that has not been backed up for a specified amount of time.
How to use the Account Cleanup Tool