The Issue Types page lists the Issue Types, along with their usage on the system, Projects and number of Issues are using this Issue Type, as well as Issue Type Schemes that contain this Issue Type.
To delete Issue Types in bulk, use the following steps:
Use the table headings to sort the table appropriately.
Select the Issue Types you want to delete by ticking the boxes on the left of each item.
Click on the Delete in button to open the confirmation page.
When you're happy, click on the Delete Now confirmation button to start the deletion, or on the Add to Queue to append a new task to the delete queue (see Task Manager).