You can manually edit bleeds to mask portions of the artwork. You can also adjust rectangular bleed margins to crop out extra image area, such as printer's marks, by using negative settings in the bleed margins.
You can edit bleeds by adding points to the bleed path and dragging the points to the desired locations, and by deleting points. Using the Geometry palette, you can adjust the positions of points and sections with greater precision.

Hold down the Option key (Macintosh) or Alt key (Windows) to add or delete points on the bleed path. The Bleed tool pointer changes appearance to indicate its current status:
 
indicates that the pointer is in position to add a point to a bleed path

indicates that the pointer is in position to delete a point from a bleed path

indicates that the pointer is too far from all points and paths to be able to perform any actions

You can select bleed points one at a time, or you can select multiple points at the same time by marqueeing them.

When you do this

This happens

Select a path segment

The two points and adjacent lines are selected

Select a single point on the path

The point and adjacent lines are selected

Drag a point when a path section is selected

The selected section moves

To add a point to the bleed path:

  1. Select the Bleed tool on the main toolbar.
  2. Hold down the Option key (Macintosh) or Alt key (Windows), and click the bleed path where you want to add a point.
  3. Drag the point to the desired location, or type coordinates in the X and Y boxes on the Geometry palette.

To delete a point from the bleed path:

  1. Select the Bleed tool on the main toolbar.
  2. Hold down the Option key (Macintosh) or Alt key (Windows), and click the point on the bleed path that you want to delete.

To move a path segment:

  1. Click the path to select it.
  2. Drag the selected segment to a new location or type coordinates in the X and Y boxes on the Geometry palette.
    Note: To constrain the movement of the section to only 45-degree or 90-degree angles, hold down the Shift key as you drag the section.

To copy a bleed path from one artwork to another:

  1. Select the Bleed tool on the main toolbar.
  2. Click the artwork placement in the layout that has the bleed path you want to copy.
  3. Select Edit > Copy.
  4. Select the target artwork in the layout, or if you want to apply the bleed path to all instances of the artwork, select the target artwork in job properties.
  5. Select Edit > Paste.