I don't use Garage Band. I keep getting update notifications, but it requires Big Sur. I have no plans on going Big Sur for sometime. It's annoying. Everyday I get the notification. Can I delete of hid this? Do I have to delete garage band?
Yes, you will need to removed GarageBand so stop getting nagged about the updates. Problem is GarageBand is protected by System Integrity Protection (SIP), so you will need to disable SIP first. If you search you can find instruction how to disable SIP.