When you use the V2 switch, help is available
$esxcli = Get-EsxCli -VMHost <MyEsx> -V2
$esxcli.vsan.storage.remove.Help()
You can create the hash table, fill in the required parameter, and then Invoke the method.
$remVSAN = $esxcli.vsan.storage.remove.CreateArgs()
$remVSAN['uuid'] = <a groupUuid>
$esxcli.vsan.storage.remove.Invoke($remVSAN)
You can loop over all ESXi nodes and then all UUIDs
