When sending out PDF documents to others, it's often a good idea to apply copy protection and other document restrictions, such as printing and editing. This will prevent unauthorised users from copying the PDF content. To properly change any restrictions, you must enter the document's permissions password in Adobe Acrobat. The permissions password is created by the PDF author in the security settings of Adobe Acrobat.
Open a PDF document in Adobe Acrobat.
Click the "Advanced" menu.
Click "Security," then "Password Encrypt."
Click "Yes" if prompted to change the security. The "Password Security--Settings" dialogue box opens.
Click the check box under "Permissions" that reads "Restrict Editing and Printing of the Document."
Enter the permissions password in the field labelled "Change Permissions Password." This password was created by the PDF author when he placed the restrictions on the document.
Click the check box next to "Enable Copying of Text, Images, and Other Content" to remove copy protection. You also can make other changes to the restrictions by making selections from the "Printing Allowed" and "Changes Allowed" menus.
Click "OK." Click "OK" again when prompted. Enter the permissions password again to confirm it. Click "OK."
Click the "File" menu, then "Save" to save the changes to the document.