There are a few ways to ensure Blaze doesn't post content that you don't want to publish. If a post is set to "Autoscheduled," one option is to delete the post permanently, which removes it from your schedule and removes the content from your workspace. The other option is to Unschedule the post, which retains the post in Draft form in your workspace, but removes it from the Autopost queue.
To delete a post permanently:
Step 1: Select the Calendar view
Step 2: If you want to permanently delete the post, from the Calendar, hover over the preview of the content you want to delete, put a check on the tick box, then choose Delete at the bottom of the Calendar view.
To reschedule content, select it from the Calendar, then use the option in the right sidebar to adjust the schedule.
To unschedule a post, click on the post you want to unschedule. Then on the preview window, choose the date dropdown on the right. Choose "Unschedule" from the options listed.
Doing so will switch the post to Draft status, ensuring it does not publish. The post should remain visible and editable in your workspace, and you can always reschedule it to post another time.