You can create the table in the right format with just the name of the hosts if you modify the second line of your script into:
Select @{N="Name";E={$_.Name.Split('.')[0]}},
If you want to modify the $hostinfo variable then you can use:
$NewHostinfo = $hostinfo | Select-Object -Property @{N="Name";E={$_.Name.Split('.')[0]}},UsedMemoryGB,TotalMemoryGB,FreeMemoryPct