Q: Delet data

Drag it to the Trash icon, and then Finder -> Empty Trash

I'm not sure I really understand your question, because what I just said is almost trivial?

Do you want to erase your disk?

Install a clean OS X?

Just remove your user account?

Some more information about what you desire would help.

hello just to let you know apple products are becoming slow if you are near enough out of storage!

Syncing your phone to iTunes on your computer should delete the old logs.