By default, the Redaction toolbar provides quick access to tools for redacting PDF content. See Redaction for details regarding redacting a PDF file. See Erase Content for another method of removing content from a PDF.
If the toolbar is currently hidden, go to View > 
Toolbars and select it to show it.
Mark for Redaction (SHIFT+R): Launches the Redaction tool for selecting content to redact.
Apply Redactions (SHIFT+A): Applies redaction selections.
Note: Redaction is only available in Bluebeam Revu eXtreme Edition.