Kill excel process using powershell only

hi,

To kill excel process, i tried using the following command

!powershell -inputformat none Stop-Process -Name "Excel"

but it gives me this error msg

The command prompt has been disabled by your administrator.

Press any key to continue . . .

The command prompt is disabled by the admin only powershell is working for me. the command works fine in powershell . but when running through Matab, it seems that the execution starts from command prompt first instead of powershell

-inputformat none Stop-Process -Name "Excel"

Please suggest any solution