How can I delete past backups to make more room for new backups. Can I delete all past backups?

I have a13" Mac Pro 2012 late fall model.I keep getting not enough space to complete backup.
When entering TIME CAPSULE, I am given option to choose 1 of 2 disks.

AirPort Time Capsule (2013)

AirPort Time Capsule (2013)

Product No Longer Available

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