Sandeep,
Is your intention to remove the password encryption or just extract data from it?
If you want to remove password encryption then you should first remove the usage rights and then remove pass encryption
If you want to just extract data from it - You can create a short lived subprocess that has unlock PDF password and extract data which should work fine (Ensure that unlock and extract are in a short lived process)
In case of long lived process when you unlock PDF password - the PDf gets unlocked and will be saved - and if you try to extract data it would fail because you need to unlock it again.
HTH
--Santosh
http://about.me/nskumar