I am a PA and starting a new job, I want to delete all of the history, tasks and headings and start fresh under this account.... any idea how?
Just create a new project. You could have multiple project so use them.
With this each time you start a new job you have a project for this.
And if you get multiple job at the same time you could keep an eye on each tasks.
If you really want to delete a project, you can just hover on a project and click on the 3-dot icon and select "Delete project". Please note that once you delete a project, there's no way to retrieve it anymore.