You didn't answer all my points, and I can't get an axfr of either doman, so this is my best shot:
You've got a separate zone file for stotlardrug.com. It has a separate MX record. Your first step would be to remove the MX record and update the zone's serial number. You can do this from the shell as root, or automatically through DNS Administration at the admin DirectAdmin login. If you do it manually through the shell be sure to reload BIND after you've finished the edit. If you do it through the DirectAdmin admin login, DirectAdmin will manage the reload.
Finally, from a root shell, edit the file /etc/virtual/domains; remove the line:
stotlardrug.com
from that file. You do NOT have to restart anything.
Jeff