Getting rid of old collaborators

[Andrew_Taylor1]

OK Guys so I have some redundant collaborators who I need to delete.
I have been into the share dialogue and removed them.
I have have deleted all tasks they were assigned to.

Yet the gosts seems to persist in my Canban views as below.

and the collaborator called internal action - I don’t seem to recall having created this.
Ultimately it results in useless columns taking up space in the Canban view as well as the legacy staff names being constantly present.
any help on getting rid of this would be appreciated!

[carter]

Did this ever get solved? I have the same annoying problem.