This means that the query that we are attempting to delete is being used as a Starting Query by another query. We either need to delete the dependant or change the Starting Query of the dependant to something else.

To change the starting query of the dependant query:
  1. Click on the name of the query you would like to delete
  2. Under Tasks, click Query Associations
  3. Click on the name of the dependant query you would like to edit
  4. Under Starting query, change it to something different
  5. Click Save And

To delete the dependant query:
  1. Click on the name of the query you would like to delete
  2. Under Tasks, click Query Associations
  3. Under the name of the dependant query, click Delete