Start with the query selecting all the relevant servers.
Select Top 1000000
tsysOS.Image As icon,
tblAssets.AssetID,
tblAssets.AssetName,
tblAssets.Domain,
tblAssets.Userdomain,
tblAssets.IPAddress,
tsysOS.OSname,
tblAssets.Description,
tblAssetCustom.State
From
tblAssets
Inner Join tblAssetCustom On tblAssets.AssetID = tblAssetCustom.AssetID
Inner Join tsysOS On tsysOS.OScode = tblAssets.OScode
Where
(tsysOS.OSname Like '%Win 2012%'
Or tsysOS.OSname Like '%Win 2016%'
Or tsysOS.OSname Like '%Win 2008%'
Or tsysOS.OSname Like '%Win 2000 S%'
Or tsysOS.OSname Like '%Win 2019%')
And tblAssetCustom.State = 1
Order By
tblAssets.Domain,
tblAssets.AssetName
Confirm that works, then add one more condition to the WHERE clause:
Where
(tsysOS.OSname Like '%Win 2012%'
Or tsysOS.OSname Like '%Win 2016%'
Or tsysOS.OSname Like '%Win 2008%'
Or tsysOS.OSname Like '%Win 2000 S%'
Or tsysOS.OSname Like '%Win 2019%')
And tblAssetCustom.State = 1
AND tblAssets.AssetID Not In (Select Top 1000000
tblSoftware.AssetID
From
tblSoftware
Inner Join tblSoftwareUni On tblSoftwareUni.SoftID = tblSoftware.softID
Where
tblSoftwareUni.softwareName Like '%Software not installed%')