I’m surprised that you’re not finding the package with locate.
To find the packages in the repo
You can use a query the repo directly like this:
reprepro -v -b /var/repos/ubuntu/building -A source listfilter trusty "Package (% *tornado* )"
trusty|main|source: ros-indigo-tornado 4.2.1-1trusty
trusty|main|source: ros-jade-tornado 4.2.1-0trusty
When doing things on the repo make sure to su to jenkins-slave to not override file permissions.
As jenkins-slave user on your repository the following command should clear the packages after listing all matches on the default repo locations.
jenkins-slave@ip-172-31-9-243:~/reprepro-updater$ ./remove_packages.py "Package (% *tornado* )"