As you know users cannot be completely deleted from your Bitrix24 account, only dismissed. This is done in purpose to keep all of your data safe. When the workgroup creator is dismissed the group is not affected. Further you may need to either appoint a new owner for this group, move the group to archive or delete it completely.
First, go to Profile & activate Admin Mode. Then open workgroup Actions menu & choose:
- Delete Group - completely & irreversibly.
- Edit Members - appoint new group owner.
To appoint a new workgroup owner first select user (whom you'd like to appoint), go to Actions menu on the right side & click Change Owner: