Hey there!
My name is Ravi, an independent advisor and expert user. I am happy to help you. :)
I understand you want to delete old backups of your computer.
1). Open the Settings app.
2). Click on Update & Security.
3). From the left-hand menu, select Backup.
4). Here, you should see any backups associated with your account. You can select and delete them as needed.
The screenshot you have shared shows the restore points of your PC. You can use Disc Cleanup to delete them.
1). Click Windows Start and then type Disc Cleanup.
2). Open the app and click ok on the next box.
3). Under the Disk Clean up for (C:) window, Windows will calculate how much space the system can save and give you a list of files to delete.
4). Click the Cleanup system files button and wait for a while.
5). Go to the More options tab. Under the System Restore and Shadow copies option, click Clean Up.
6). Confirm the process.
Feel free to get in touch again if you have any additional questions.
Cheers,
Ravi