You can remove selected devices from the disk group, or you can remove an entire disk group.
Because removing unprotected devices might be disruptive for the vSAN datastore and virtual machines in the datastore, avoid removing devices or disk groups.
Typically, you delete devices or disk groups from vSAN when you are upgrading a device or replacing a failed device, or when you must remove a cache device. Other vSphere storage features can use any flash-based device that you remove from the vSAN cluster.Deleting a disk group permanently deletes the disk membership and the data stored on the devices.
Note: Removing one flash cache device or all capacity devices from a disk group removes the entire disk group.
Evacuating data from devices or disk groups might result in the temporary noncompliance of virtual machine storage policies.