https://wiki.jenkins.io/display/JENKINS/Installing+Jenkins+on+Ubuntu

https://www.digitalocean.com/community/tutorials/how-to-install-jenkins-on-ubuntu-16-04

If your jenkins is running as service instead of process you should stop it first using

sudo service jenkins stop

After stopping it you can follow the normal flow of removing it using commands respective to your linux flavour

For centos it will be

sudo yum remove jenkins

For ubuntu it will

sudo apt-get remove --purge jenkins

if you are ubuntu user than try this:

sudo apt-get remove jenkins

sudo apt-get remove --auto-remove jenkins (worked)

https://www.vultr.com/docs/how-to-install-apache-maven-on-ubuntu-16-04