This is a Virtual Machine Rollback Settings which is configured at LCM.
VMs will show this snapshot at the Snapshot Manager tab of the VM.
By default, vSphere Lifecycle Manager takes snapshots of virtual machines before upgrading them. If the upgrade fails, you can use the snapshot to return a virtual machine to its state before the upgrade. You can configure vSphere Lifecycle Manager to keep snapshots for an indefinite or fixed period of time.
You can either delete the LCM based snapshot manually, and alternatively go into Lifecycle manager and configure a time limit on the snapshots as mentioned below-
That way it will remove the snapshot after whatever length of time you configure - It can be set to as maximum as 100 hours.