Check the kishorilal comment
https://www-secure.symantec.com/connect/forums/remove-dlp
DLP agent is install with the password. Which can be remove it with the help of UninstallPwdKeyGenerator.exe
Kishorilal comment
DLP agent will install with any password that you provide but during uninstallation it will compare the inbuilt PGP hash value of provided password.so that initially you need to add hash generated password which can be genreated throgh PGP.dll and Uninstallation password provided by symantec.
In your case your correct password is converted to internally hash and mismatches.Read below.
The UninstallPwdKeyGenerator.exe creates an uninstall password key which is used within Install_Agent.bat.
The UninstallPwdKeyGenerator.exe is included with the 11.1 Agent Tools. This tool is used to generate the value you use for UNINSTALLPASSWORDKEY within the Install_Agent.bat file.
The tool must be in the same directory as PGPsdk.dll.
The following is an example of how to create a key hash to use for the UNINSTALLPASSWORDKEY value.
UninstallPwdKeyGenerator.exe -xp=the-password-you-want-to-require-for-uninstalling-edpa
example output of tool: 8D98A265FFFC7C42CD4860AAE01DB23D957F8F9E
example format to use in Install_Agent.bat UNINSTALLPASSWORDKEY="8D98A265FFFC7C42CD4860AAE01DB23D957F8F9E"
example format to use with Uninstall_Agent.bat UNINSTALLPASSWORD="the-password-you-want-to-require-for-uninstalling-edpa"