Execute Process with current User

Hi,

I have a use case where the user will create a background task, the task is picked by agentservice and executes it using super user privileges.

But i want it to run using the normal user privileges, i am unable to achieve this with the code 

Aras.Server.Security.Identity plmIdentity = Aras.Server.Security.Identity.GetById(currentUserId);
bool permissionWasSet = Aras.Server.Security.Permissions.GrantIdentity(plmIdentity);

How do i achieve this ?

Thanks,

Lokesh Dogga.