The creator of a report has the ability to delete the report from the "Report Actions" drop down.
When you are editing your custom report, select the "Report Actions" dropdown and select "Delete this Report".
A message will show for you to confirm if you want to delete the report.
If you confirm that you would like to delete the report, the report will no longer exist.
If you delete this report, you will not be able to recover it again.
If you want a similar report to this, you will need to recreate it.
If your report is a Company Report, your team will no longer have access to it.