I think that is the preference of the user.
What you can do is to add #toolbar=0
to the end of the URL.
For example,
http://DOMAIN/FILE_NAME.pdf#toolbar=0
Something you might want to do is:
<embed src="MyFile.pdf#toolbar=0&scrollbar=0&navpanes=1" width="530" height="300" />
For details of parameters, please visit PDF Open Parameters.