how to stop tomcat7 in ubuntu?

Generally any service in Ubuntu can be managed by

sudo service <service_name> <argument>

Here service_name stands for name of the service, in your case it is tomcat7.

Argument stands for type of the action like start,stop,restart,status, in your case it is stop.

so finally you can stop tomcat7 with this below command.

sudo service tomcat7 stop