Blackball
If you've been 'blackballed' you've been banned from joining an organisation because of something you've done
Why it matters
Moving away from terms which infer positive or negative connotations associated to colour and colour binary (e.g. Black = Bad and White = Good) to distance from cultural views of good & evil, especially related to skin colour or appearance. Specifically, this associates 'black' with exclusion and bans.
Instead try saying:
Further External Reading Link