If the marks are in their own layer, you can just turn off that layer, and the marks should be gone. Use View>Show/Hide>Navgation Panes>Layers to show the layers pane.
If the marks are outside of the box that describes the page content, you can just set to crop box to e.g. the art box, and that will remove the marks. You can do this in Tools>Print Production>Set Page Boxes for this.
If that does not work, you can use content edit to remove them. This is the most involved solution: Use Tools>Content Editing>Edit Text and Images, then draw a rectangle around the a group of elements that you want to remove and hit the delete key.