You can get rid of old imported data by 2 ways:

• Deleting the imported Project: Your previously imported data will be visible in the lists of Yodiz Projects . You only need to delete your project in which your Jira data is imported earlier.
  • Go to Settings > projects and Users > Manage Projects. Then delete your project in which Jira data exists.
• Select and Bulk Delete Imported Items:If you want to delete only some selective User stories from the project or you already had user stories in selected project before importing data from jira, then:
  • Go to Backlog.
  • Select project in which Jira data exist.
  • Mark User Stories and then use bulk delete to get rid from old data.