Can't delete /var/lib/pgsql - Device or resource busy

Moving my pgsql directory to another volume I encountered an issue with being unable to rename or remove /var/lib/pgsql (in order to replace it with a symlink). Despite postgresql being stopped and even disabled in systemctl I kept getting this error:

**#** rm -r pgsql                  
rm: cannot remove 'pgsql': Device or resource busy

I tried lsof to findout which process is using it but with no luck:

**#** lsof +D /var/lib/pgsql
lsof: WARNING: can't stat() fuse.gvfsd-fuse file system /run/user/1000/gvfs
      Output information may be incomplete.

So I was forced for now to keep this folder and to symlink its content instead.