Why can a PDF block printing at all?
The format lets an author set permission bits — print, copy, modify, annotate, fill forms, extract for accessibility, assemble, print at high resolution. They live inside the encryption dictionary, and readers are expected to honor them.
They are honored by convention, not by cryptography: the document itself is readable, which is why it opens without a prompt. That is also why removing them is a matter of rewriting the file rather than breaking anything.
Is it your file to unlock?
The everyday cases are your own documents: a statement you need to print, a ticket you need to show, a form you are asked to fill in, a manual you bought. Restrictions are often switched on by default by whatever produced the file, and nobody intended to stop you.
Where a restriction reflects a license you agreed to — a paid report you may read but not redistribute — removing it does not change the agreement. That is a decision about the license, not about the file.
What if it asks for a password before it opens?
Then it is encrypted with a user password, and no permission flag is involved. You need that password, and then a decrypted copy can be saved. No tool here guesses it.
Files sent by banks and insurers are almost always this kind, with the password described in the covering email.