I saw some users before deleted some of their old posts even though they had posts more than the activity but still their accounts went ranked down.
How is that even possible, could that have been a glitch?
~snipped~
That's the only reason I could see as to why you'd be concerned about keeping your rank, and if you were going to leave bitcointalk altogether it doesn't make sense why you'd care.
I think OP isn't thinking of absconding from the forum. Otherwise they wouldn't be asking. They would just abandon it and take a walk, knowing that this forum isn't tied to their umbilical cord. What I think necessitated OP's question is that they want to know how to be on the safe side by not tampering with their rank if they went on deleting some of their posts in order to possibly keep a clean post history.