Questions about CFW/HEN in general and accounts and ps3 ownership

so i've been thinking of installing hen temporarily on mine to see what temps its running for research purposes and i dont plan to go online with it in the meantime but i dont even want sony ever knowing thats its or was modified as i would like to keep my psn account away from harm and possibly the ps3 too. would de-activating the system whilst is OFW and deleting psn users from the ps3 will be enough ?

so in scenario 1
person 1 owns a ps3 then sells it gives it away whatever, person 2 now...

Questions about CFW/HEN in general and accounts and ps3 ownership