I have my login ID for OTN and OPN as official ID. All my certifications are links and show up on my OPN page. Can I change the login IDs as I am worries what will happen tomy certifications etc once I leave the company.
My Pearson and OPN are linked to each other with my company ID.
Well your OTN information is controlled via the 'Your Control Panel' link at the top-right of the forums page you are currently viewing (assuming you're signed in to OTN). You can change the email/etc there. I use a personal email address for mine rather than a company email for the reasons you note in your post.
I've never been an employee of an OPN, so I don't know about changing that. However, if you leave the company, presumably you will no longer be an OPN employee and therefore I would think that account/login would go away anyway. I may be wrong -- as I said, nothing I have personal knowledge of.
Pearson links to your Oracle Certification identity via your Oracle Testing ID. This won't change as you move from company to company. If you are currently logging in to Pearson using your work email, you likely want to change that. You can do that from the Pearson Vue site. I don't know the details offhand. Login and look for a 'My Settings' or 'My Accout' link (or something similar). Again, I'd use a personal email address rather than a work one for contact info.
When you leave the OPN company, you'll need to login to your Oracle Web Account and update your email ID if you are currently using your company email address as your user name. After that, you'll need to contact Oracle Certification Support to let them know that you've updated your user name (email address) and provide the new email address. They will re-link your CertView account (where you view all certification history) to your new user name in your Oracle web Account.