Locate the Presentation you would like to reorder in the Viewpoints panel (right toolbar). Click it to open the detailed mode.

Hover over the Viewpoint you would like to move, click on the six dots to the left of the Viewpoint and drag it to the new position.

Locate the Presentation that you want to remove a Viewpoint from.

Open the three-dot menu on the Viewpoint you’d like to remove. Select "Remove from the presentation"