crontab doesn't like empty files on SunOS

So, I have a one line crontab file on an old unix machine. I tried to get rid of it by deleting it, and saving the file, but that did not take.

After some research, it seems like crontab on SunOS does not like it when you try to save an empty crontab file. The way to do this on SunOS is

crontab -r your_username