Your V11 tags do not get deleted as you upgrade to the V12 deck on AnkiHub. However, these are no longer needed.
To delete the V11 tags:
- Go to Browse on Anki
- On the left-hand side, navigate to tags
- Find all instances of #AK_Step1/2_11
- Right click on the tag
- Delete
See this tutorial for more detail
All V11 tags are now deleted!