Run these following command to remove solr from your system. The version I was using is 8.9.0. If you have installed a diffrent version then symply put your version instead of 8.9.0 in the command.

sudo service solr stop 
sudo rm -r /var/solr
sudo rm /etc/init.d/solr 
sudo rm -rf /opt/solr 
sudo rm -rf /opt/solr-8.9.0
sudo rm -rf /etc/default/solr.in.sh