doe sthis helps

https://www-secure.symantec.com/connect/forums/sep12-requires-uninstall-password-was-never-set

Try password as: symantec

NOTE: Uninstall Password would come up only when this policy is set. Check the Policy from SEPM> Clients > Policies > General-security settings.

Use the following to disable password and remove the product.

1. Open the registry
2. Navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Symantec\Symantec Endpoint Protection\SMC
3. Change the value for SmcGuiHasPassword from 1 to 0
4. Restart the SMC service

Then uninstall the product :)

Reference: https://www-secure.symantec.com/connect/forums/password-prompt-uninstall-symantec-was-not-provided-during-install-how-do-i-uninstall-without

 you don't have any uninstall password change registry setting.

HKEY_LOCAL_MACHINE\SOFTWARE\Symantec\Symantec Endpoint Protection\AV\AdministratorOnly\Security\UseVPUninstallPassword

Set to 0 to disable

Hi,

There are two ways i.e. either remove it from SEPM console or Change the registry settings on the machine itself.

There is no default password set when you first install SEPM first time.

Hello,

How to manually uninstall Symantec Endpoint Protection client from Windows 2000, XP and 2003, 32-bit Editions

http://www.symantec.com/business/support/index?page=content&id=TECH102261

OR

If you don't have any uninstall password change registry setting.

HKEY_LOCAL_MACHINE\SOFTWARE\Symantec\Symantec Endpoint Protection\AV\AdministratorOnly\Security\UseVPUninstallPassword

Set to 0 to disable

OR

You can use Symantec Cleanwipe Utility. To receive the Utility, you need to contact Technical Support.

Check this Thread which have same query - 

https://www-secure.symantec.com/connect/articles/how-uninstall-symantec-endpoint-client-if-uninstall-password-place

and this Article - 

https://www-secure.symantec.com/connect/forums/sep12-requires-uninstall-password-was-never-set

Hope that helps!!