Log into Blackboard and access your Blackboard course.  Hover your cursor next to the link you want to hide, and click on the chevron button that appears next to the link.

Select Hide Link from the menu that pops up on screen.  The hidden link will then be marked with a square with a slash through it next to the link.

Locate the link you want to show to students, and hover your cursor over the link you want to show.  Click the chevron button that appears next to the link.

In the menu that appears, click on Show Link. The link will now be visible to students.