[exim] How do you delete a large frozen queue?

Hello.

I tried searching the docs and the mailing list, unsuccessfully.

One of the accounts on a linux server I run was hacked, and the hacker has
sent many and now queued several hundred thousand spam emails.

The disk holding exim ... /var/spool/exim ... is 100 percent full.

The exim and exiqgrep commands still function, but there are so many messages
that any attempt to form a pipe exits in error.

Since I don't seem able to delete all messages from that sender, I am ready to
delete all messages in the queue (or queues if that is the case; I am new to this).

I can delete and re-create the directories /var/spool/exim/input and /var/spool/exim/msglog
but I don't know if there is anything needed inside those directories.

Any suggestions by someone knowledgeable?

Thank you.

Steve Albin