Edit ▸ Redact works in two stages so you can review before anything is destroyed: 1. Mark Selected Text for Redaction or Mark Area for Redaction… — as many marks as you like; Remove All Redaction Marks clears them. 2. Apply Redactions… — asks "Apply N redactions?" and then does it for real: the hidden text is gone from the file, not covered by a black rectangle someone could remove.
Redact Selected Text Now and Redact Area Now… do both stages in one go, after a confirmation. If nothing could be redacted, the app says so and why. There is deliberately no keyboard shortcut.