In our project, we use defined components for expressing "where" the work happens. But since the last update of jira, everyone can create a new component in the issue sreen; when choosing the components for the issue.
And so it happens, that we have new components because some of the colleagues don't look at their typing .
One possibility is of course talking to them and clean the components from time to time, but it would be nicer, if that possibility could be deactivated. And I just don't find the right place...
We use JIRA v6.4.7.
To create a component, a user must have "project administration" rights. Generally, you don't want most of your users to have that - it should be your project lead/owner and scrum master. Consider removing it from your users.