You can delete custom question templates that you created but not default question templates. 

1. Click … in the toolbar of question types.

2. Click the name of the custom question template that you want to delete. 
   Note: You cannot delete the default question templates (Multiple Choice, Range, Yes/No).

3. Click on Manage Question Templates, then click the trash icon for the template that you want to delete. Deleting a question template has no effect on the forms and you are not asked to verify your decision to delete.