Depending on what you want to do exactly you could use either the Release hook to release the planned orders or use the Post plan processing hook to mark the planned orders as released without actually releasing them. The hooks are described in document id 976328.1
Thanks Geert for your response. I started working on another requirement after that and did not get a chance to work on this.
Can I use the same hook to change the Action on the Planned Order. My requirement is to set the Action of the select Planned Orders to "None" from a Custom OAF Page.
Thanks in advance.