Delete tokens, which are no longer required

I guess, this is a bug where I always need Marketo Support:

If I clone a program with tokens and I delete some tokens in the mailing, because I don`t need them here, I am not able to delete the same tokens in the tokens tab. It still says, that they are used, although the do not exist anymore in my mailing (hmtl & text version).

It only works in that way:

1. unlink my mailing from all campaigns
2. unapproving mailing
3. deleting mailing
4. deleting tokens
5. cloning the mailing from another program
6. updating the mailing
7. linking the mailing to my campaigns

that is very time consuming. Maybe Marketo can solve that bug.