Hello, ad!

a> Hi,
a> How can I add an user account into Administrators?
a> and how to remove the account from Administrators?

You can use Win32 API for that, namely NetGroupAddUser and NetGroupDelUser both defined in
Netapi32.dll.

You will have to use P/Invoke to call them from C#

--
Regards, Vadym Stetsyak
www: http://vadmyst.blogspot.com

plz refer to here.

http://www.pinvoke.net

you will find more information about how to use WIN32 API  in the .NET
platform.

Good luck.

Sincerely,
simida

Take a look at the System.DirectoryServices namespace, these classes are
build to provide this functionality, no need to take the PInvoke tour.
Start here
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vbcon/html/vbco
nwhatyouneedtoknowaboutactivedirectoryadsi.asp
and search MSDN for more samples.

Willy.

http://msdn2.microsoft.com/en-us/library/ms180833.aspx has a lot of samples
(AD only).

Willy.