Usar con los script de inicio en gpedit.msc, user logon scripts.

<#
.SYNOPSIS Disable Teams autorun

.NOTES
-2019-08-30 - Updated to call Stop-Process -Name Teams before modifying config file.
		    - Set output encoding to UTF8.
-2019-08-12 - Original release
#>

# If Teams autorun entry exists, remove it
$TeamsAutoRun = (Get-ItemProperty HKCU:\Software\Microsoft\Windows\CurrentVersion\Run -ea SilentlyContinue)."com.squirrel.Teams.Teams"
if ($TeamsAutoRun)
{
	Remove-ItemProperty HKCU:\Software\Microsoft\Windows\CurrentVersion\Run -Name "com.squirrel.Teams.Teams"
}

# Teams Config Data
$TeamsConfig = "$env:APPDATA\Microsoft\Teams\desktop-config.json"
$global:TeamsConfigData = Get-Content $TeamsConfig -Raw -ea SilentlyContinue | ConvertFrom-Json

# If Teams already doesn't have the autostart config, exit
If ($TeamsConfigData)
{
	If ($TeamsConfigData.appPreferenceSettings.openAtLogin -eq $false)
	{
		# It's already configured to not startup
		exit
	}
	else
	{
		# If Teams hasn't run, then it's not going to have the openAtLogin:true value
		# Otherwise, replace openAtLogin:true with openAtLogin:false
		If ($TeamsConfigData.appPreferenceSettings.openAtLogin -eq $true)
		{
			$TeamsConfigData.appPreferenceSettings.openAtLogin = $false
		}
		else
		# If Teams has been intalled but hasn't been run yet, it won't have an autorun setting
		{
			$Values = ($TeamsConfigData.appPreferenceSettings | GM -MemberType NoteProperty).Name
			If ($Values -match "openAtLogin")
			{
				$TeamsConfigData.appPreferenceSettings.openAtLogin = $false
			}
			else
			{
				$TeamsConfigData.appPreferenceSettings | Add-Member -Name "openAtLogin" -Value $false -MemberType NoteProperty
			}
		}
		# Save
		$TeamsConfigData | ConvertTo-Json -Depth 100 | Out-File -Encoding UTF8 -FilePath $TeamsConfig -Force
	}
}