Yes and No, you cannot delete documents that have been either sent for approval to step 2 in a workflow and first section is approved, or a published document can not be deleted.
Only documents that are in progress by you and have not been sent for approval in step 1 is documents you can delete. These can be deleted in 2 ways.
1. Open the document in read mode and click on the edit button in top right corner
2. Click on the delete button
3. Approve that you are sure you want to delete the document or revision by clicking on delete
Second Option: (if your superuser has enabled this option)
1. Go to the report and find the document
2. If your superuser has activated this option you will see a delete column in the index, from here you can delete your documents that has the Trash bin as you can see above on row 2.
If this column is not in your report, contact your superuser and ask if that is something you can have.