A week or so ago I tried to compile vsftpd from source but I wanted to reinstall. I cant recall exactly how I installed it as I can nto find the tutorial I used now, but going off memory the install procedure seemed a bit strange compared to the usual ./configure, make, make install. So I wanted to reinstall using the official INSTALL file instructions this time.

So I ran:
dpkg -r vsftpd
Then:
dpkg --purge vsftpd

but I see a few files left over when I run "locate vsftpd" and wanted confirmation it is safe to remove them.
Actually I am confident it is safe to manually remove all of them with the exception of /usr/local/sbin/vsftpd. So is it safe to remove that and reinstall/recompile?

Well, I don't know dpkg, but in the rpm system, you can say
to check what the pkg db knows about.
I'd assume dpkg has an equivalent?

Use this command to remove/delete every files including configuration files -

And then after that you can reinstall the package, fresh.

I already did a purge and the files listed above where still left behind. I did an updatedb to make sure the db wasn't out of date, and the files were still there so I removed them all manually. Thank you guys both for your responses!

Exactly, removing the files manually was another solution to this and reinstall the package.

if he wants to reinstall some of these files can be reused.