Activity dependencies can be edited, disabled or deleted. However, the project end date will be affected when:
i) Disabling an activity dependency in the critical path and subsequently advancing the start date for this activity will advance the project's end date.
ii) Enabling an already disabled activity dependency in the critical path will delay the project's end date.
iii) Deleting an activity dependency which have multiple predecessor dependencies may affect the project end date.
The list of dependencies on the activity are shown under the Dependency List given on an activity.
The following steps will guide you to edit activity dependencies:
Double-click on the activity bar and then click on Dependency List.
To edit a particular dependency, hover over the Name of the dependency, click on the Edit (Pencil icon) shown beside the predecessor or successor activity displayed.
After the required changes are done, click on Save to update the dependency.
Enable / Disable dependencies:
By default all dependencies are enabled. The button to the left of the dependency is always turned on. To disable a dependency, click the button on the left provided.
Once a dependency is disabled (or deleted), the previous predecessor/successor activity will not affect the activity.
However, if an activity is in the critical path, it will affect the end date of the overall project completion date.
The steps to edit task dependency are similar to editing activity dependency. Read 4.9 Edit Task Dependency to know more.