Removing square brackets from column headers DAX query

Ah yes so, as my code is above the table name precedes the column name in the square brackets. However, I've used SELECTCOLUMNS to get around this, so the script is now (first five columns as an example in the DAX query);

[System.Reflection.Assembly]::LoadWithPartialName("Microsoft.AnalysisServices.AdomdClient") 

$PowerBIEndpoint = "REDACTED"
$PowerBILogin = ""
$PowerBIPassword = ""

$Query = 
"EVALUATE
SELECTCOLUMNS (
    SUMMARIZECOLUMNS (
        'XactlyTemplate'[Performance Month],
        'XactlyTemplate'[Invoice Number1],
        'XactlyTemplate'[Transaction Date],
        'XactlyTemplate'[Customer Unique ID],
        'XactlyTemplate'[Customer Name],
        'XactlyTemplate'[Customer State],
        'XactlyTemplate'[Customer Region],
        'XactlyTemplate'[ContractID],
        'XactlyTemplate'[Contract Start Date],
        'XactlyTemplate'[Contract End Date],
        'XactlyTemplate'[Order/Contract Term in Months],
        'XactlyTemplate'[Order/Contract Term in Days],
        'XactlyTemplate'[Usage Type],
        'XactlyTemplate'[AcctAssignGroup],
        'XactlyTemplate'[Revenue Type],
        'XactlyTemplate'[Transaction Type Description],
        'XactlyTemplate'[Stock_Material Code],
        'XactlyTemplate'[Stock_Material Code Description],
        'XactlyTemplate'[Product Name],
        'XactlyTemplate'[Sub-Product],
        'XactlyTemplate'[Recurring/Non-Recurring],
        'XactlyTemplate'[Currency],
        'XactlyTemplate'[Sales Org],
        'XactlyTemplate'[Business Unit],
        'XactlyTemplate'[Partner Account],
        'XactlyTemplate'[Partner Name],
        'XactlyTemplate'[Sales Team],
        'XactlyTemplate'[Employee_ID_2],
        'XactlyTemplate'[Employee_2_Split_Percentage],
        'XactlyTemplate'[Employee_ID_3],
        'XactlyTemplate'[Employee_3_Split_Percentage],
        'XactlyTemplate'[Employee_ID_4],
        'XactlyTemplate'[Employee_4_Split_Percentage],
        'XactlyTemplate'[Employee_ID_5],
        'XactlyTemplate'[Employee_5_Split_Percentage],
        'XactlyTemplate'[Employee_ID_6],
        'XactlyTemplate'[Employee_6_Split_Percentage],
        'XactlyTemplate'[Employee_ID_7],
        'XactlyTemplate'[Employee_7_Split_Percentage],
        'XactlyTemplate'[Employee_ID_8],
        'XactlyTemplate'[Employee_8_Split_Percentage],
        'XactlyTemplate'[Employee_ID_9],
        'XactlyTemplate'[Employee_9_Split_Percentage],
        'XactlyTemplate'[Employee_ID_10],
        'XactlyTemplate'[Employee_10_Split_Percentage],
        'XactlyTemplate'[Employee_ID_1],
        TREATAS ( { DATE ( 2020, 9, 1 ) }, 'XactlyTemplate'[Performance Month] ),
        `"No_of_Units`", CALCULATE ( SUM ( 'XactlyTemplate'[# of Units] ) ),
        `"Total_Amt`", CALCULATE ( SUM ( 'XactlyTemplate'[Total Amt] ) ),
        `"Employee_1_Split_Percentage`", CALCULATE ( SUM ( 'XactlyTemplate'[Employee_1_Split_Percentage] ) )
    ),
    `"Performance_Month`", 'XactlyTemplate'[Performance Month],
    `"Invoice Number`", 'XactlyTemplate'[Invoice Number1],
    `"Transaction Date`", 'XactlyTemplate'[Transaction Date],
    `"Customer Unique ID`", 'XactlyTemplate'[Customer Unique ID],
    `"Customer Name`", 'XactlyTemplate'[Customer Name]
)"

$ExportPath = "REDACTED\DataExport.csv"
  
$Connection = New-Object -TypeName System.Data.OleDb.OleDbConnection
$Results = New-Object System.Data.DataTable
$Connection.ConnectionString = "Provider=MSOLAP.8;Data Source="+ $PowerBIEndpoint +";UID="+ $PowerBILogin +";PWD="+ $PowerBIPassword  
$Connection.Open() 
$Adapter = New-Object -TypeName System.Data.OleDb.OleDbDataAdapter $Query ,$Connection
$Adapter.Fill($Results) 
$Results | export-csv -Path $ExportPath -NoTypeInformation -Encoding UTF8noBOM
$Connection.Dispose()
$Connection.Close()

Which outputs;

"[Performance_Month]","[Invoice Number]","[Transaction Date]","[Customer Unique ID]","[Customer Name]"

So still retaining the square brackets. The aim would be to replace them with nothing.

As for the switch, that's because of the companies use of MFA but I intend to request a service account when I get this working, for now its a proof of concept so testing on my account with MFA is sufficient.