Like Hassaim said, it is an "administrative share" which means that only an administrator would be able to access it remotely or map it like \\servername\c$.
By default, if you delete the C$, D$, etc.. Administrative shares, they will be recreated when you reboot. To disable this feature, edit:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\LanmanServer\Paramaters Double click on AutoShareServer and set it to 0 to disable it for a server. Double click on AutoShareWks and set it to 0 to disable it for a workstation. If the entries are not present, Add Value of type REG_DWORD. The Range is 0 (disable) or 1 (enable - the default). And backup the registry before editing it!