If for any reason you want to uninstall proftpd in Directadmin and don't want to run any FTP server at all. Here is a guide on how to complete it.
You should see an output similar to the following:
2.0.0 (rev: 1631)
You need to have CustomBuild 2.x to succeed with this guide. It won't work if you have 1.x version.
cd /usr/local/directadmin/custombuild ./build update ./build set ftpd no
Make sure you see ProFTPd and/or PureFTPd in a output as the following:
ProFTPd installed, but not enabled in options.conf: './build remove_proftpd' If you want to remove all the suggested programs above, run: ./build remove_items
./build remove_proftpd ./build remove_pureftpd