You could do something like this.
Note: with the -contains operator you can only check against full name, no masking characters.
If you want to check for part of a name (like local*), you coan use a RegEx expression.
Note that in a RegEx expression the vertical bar is the OR. So in the example the datastorename shall not contain 'local' or 'otherundesired'.
$undesiredDatastores = "local|otherundersired"
$report=Get-Datastore |
Select Name,
@{N='UsedPerc';E={($_.CapacityGB - $_.FreeSpaceGB)/$_.CapacityGB}} |
where{$_.UsedPerc -ge 0.9 -and $_.Name -notmatch $undesiredDatastores} |
Select Name |
Sort-Object -Property Name
