You can easily remove Client Notes individually.
To view all your Client Notes, Note Topics is the first column on the Notes board. You can use this to sort and filter your notes.
The Client Column is the second column, you can also use this to Sort and Filter your Notes by Client.
The body of the Notes page is the list of Notes with their details, clicking on a Note will open a Details Tile of the note.
Click on the Client Note that you want to remove, this will open the Details Tile for a task. Select the pencil icon on the top right.
Make your Edits and then Save the Note.
All edits made will be saved automatically.