Note: Only category Owners have the right to change the sharing options of the respective category.

1. Go to Manage > Labregister.
2. Open the to-be-unshared category.
3. Click on the Options at the top right of the page
4. Choose Manage permissions from the list
5. Click on Manage in the respective role.
6. Select from the list which users you'd like to unassign from a certain role by unchecking the box next to their name.
7. Confirm the changes by clicking Save.