Access the devtools window by clicking on the gear icon in the toolbar.
In console:
window.localStorage.clear();
You can create some fake apps by pasting something like this into the console:
var leapAppFactory = require('./test/support/leap-app-factory.js');
var leapApps = global.uiGlobals.myApps;
for (var i = 0; i < 4; i++) {
leapApps.add(leapAppFactory.storeAppData());
}
leapApps.first().save();