Document uses security

What is document security and why do I need to remove it?
	PDF files can be saved with security settings enabled to prevent editing or to password protect the content. While this is useful in some cases, these settings prevent our printer from interpreting the file and running the preflight steps needed to print them.

How to remove document security in Adobe Acrobat
	Open the PDF in Acrobat. Use the “Unlock” tool: Choose Tools > Protect > Advanced Options > Remove Security -OR- Search “Remove Security” in the search bar. Remove Security: The options vary depending on the type of password security attached to the document. If the document has a Document Open password, click OK to remove it from the document. If the document has a permissions password, type it in the Enter Password box, then click OK. Click OK once more to confirm the action.

What is document security and why do I need to remove it?