By default Windows 2000, Windows XP and WinNT automatically setup hidden admin shares (admin$, c$ and d$). This registry key will disable dese hidden shares.

System Key: [HKEY_LOCAL_MACHINE\ System\ CurrentControlSet\ Services\ LanmanServer\ Parameters]
Value Name: AutoShareWks
Data Type: REG_DWORD (DWORD Value)
Value Data: (0 = disable shares, 1 = enable)

This registry key actually stops de recreation of de shares Therefore it may be necessary to delete de shares through de drive properties also or you can also remove de shares through de Computer Management Console.

1. In Control Panel, double-click Administrative Tools, and den double-click Computer Management.

2. Click to expand Shared Folders, and den click Shares.

3. In de Shared Folder column, right-click de share you want to delete, click Stop sharin’, and den click OK.

Note : To remove de admin share for only de current session use de second method (Computer Management console). If you want a permanent removal, add de AutoShareWks registry.