You cannot erase OrganizationalEntity for sure..
But yes you can veto the BAMTaskEventListener if you are not planning to use the Dashboard module... Just for you to know, collecting the data of the process execution is a very normal and regular practice.. As soon as you start using the engine the business users will want to see statitics about the executions.. so if you veo that listener you will end up with nothing about that.
Cheers