How does one delete old mailing lists?

How does one delete old mailing lists?

The '...' menu, usually used to add email addresses or rename or delete lists, is not appearing for me on either Chrome or Edge. This is a bit frustrating as it's impossible to organise any aspect of my campaign settings.

Either I'm being daft or it's recently been broken, superseded or withdrawn, because I'm sure it was there before. The help page above is where I went to solve this problem but the '...' menu is available neither from the 'Mailing Lists' pane on the left, nor in the larger window on the right when a list is chosen. Where should I be going to invoke it?