Disable IPv6

Yes certainly you can disable the IPV6 without harm if your not using iv6 enabled applications in your infrastructure.

There are some instances where it is offered to disable ipv6 http://support.microsoft.com/default.aspx/kb/952842

to completely remove the ipv6 from your computer please do the following

    
Right Click Network Places
Select Manage Network Connections For each enabled and used NIC
Right Click - Local Area Connection - Select Properties
Networking Tab                               
DeSelect IPv6
Close

after doing the above procedure you might have to use the registry editor aswell to completely disable the ipv6 tunnel

To completely disable IPv6 on a Windows Server 2008-based computer yourself, follow these steps:

1. Open Registry Editor.
2. Locate the following registry subkey:
   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip6\Parameters
3. In the details pane, click New, and then click DWORD (32-bit) Value.
4. Type DisabledComponents, and then press ENTER.
5. Double-click DisabledComponents, and then type 0xffffffff in Hexadecimal or 4294967295 in Decimal.
   
   Note The 0xffffffff value or the 4294967295 value disables all IPv6 components except for the IPv6 loopback interface.