By modifying the reg key AutoShareWks key (1 or 0), you can enable or disable the admin share.
Note, this does not require a reboot.
The reg key
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanManServer\Parameters Name: AutoShareWks Data Type: REG_DWORD Value: 1
A script (to enable the admin share)
@echo on reg delete "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanManServer\Parameters" /v AutoShareWks /f ping -n 2 127.0.0.1>nul reg add "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanManServer\Parameters" /v AutoShareWks /t REG_DWORD /d 1 /f exit /b 0
Notes
reg add HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System /v LocalAccountTokenFilterPolicy /t REG_DWORD /d 1 /f