After a tasks is deleted from a project, the WBS does not re-number the WBS Sort.
This is working as designed. After a task is deleted the sort numbers for the remaining tasks stay the same. If the numbers do get reset (particularly for large projects) this could cause performance issues if all further tasks are re-numbered. Maintaining WBS numbers also helps for tracking purposes for those using WBS numbers as references for tasks.
If you identify a use case where the benefits of re-numbering would out weight the performance implication, our teams would like to review it via the User Community Ideation. The Idea feature of the Clarity Global User Community is at: https://communities.ca.com. If you are not a member of the Clarity Global User Community, we encourage you to join today.