help with full zfs "partitions" - can't delete files

The problem:

FreeBSD 13.3 amd64 system, with
a zfs pool built from two physical drives.
The zfs pool has 7 "partitions" (is that what they're called?)

I was copying files over from another machine and didn't realize that
I filled one of the partitions.

I can't proceed now with this one full partition.
Every single command fails due to "out of space".

That includes:
rm (one file or many)
dd if=/dev/zero of=(some file)
truncate (somefile)
zfs destroy poolname/partitionname
cannot destroy 'poolname/partitionname': out of space

There are no snapshots, I never created any.

Extensive googling has not shown any more than bug reports acknowledging
that this is a problem.

How do I fix this, short of burning the machine to the ground and starting
over?

Thanks,
Bill Dudley

This email is free of malware because I run Linux.