[mythtv-users] Can't seem to delete channels

[f-myth-users at media.mit.edu]

So I'm deleting a zillion channels from my newly-installed v31 setup.
I'm using the "international" xmltv grabber because that's the menu
setting in mythtv-setup which uses tv_grab_zz_sdjson_sqlite.  I went
to https://www.mythtv.org/wiki/XMLTV and followed the instructions
to use sdjson-sqlite-select to set a bunch of channels to be disabled.
[In modern distros, the shebang must say python3, not python, but
after changing that and installing python3-pymysql, it ran fine.]
That part of the process seemed to work; using --list afterwards
showed me that all the callsigns I disabled now have ! prepended.
[I didn't try to use the channel editor at all.]

Then I ran mythfilldatabase.  It downloaded new listings and stuffed
them into the backend.  However, all the channels I tried to delete
(a) still show up in mythweb, and (b) appear to have data all the way
out to the end of my schedule.  (This is particularly obvious because
mfdb had been failing for the last two days before this test from an
error I'd made earlier and just noticed, so in theory it grabbed a
couple days of data this time.)

Is there some other step I should be doing to make these channels go
away, both from my channel listing page and from the viewpoint of the
scheduler, so it doesn't try to record any of them?  Obviously I can't
go to Schedules Direct and edit my lineup, since I'm using the JSON
service for this box and not DataDirect.

Thanks!