This is an issue I've had for years, it's a known malware incorporated in the bitdefender total security software, I had to write a batch file to run at startup to uninstall it....
...I renamed the remnant installation folder, booted in safe mode to clean out additional fragments that did not uninstall correctly, and have reinstalled the product for the remainder of my subscription
...In the meantime, perhaps a workaround would be to uninstall Bitdefender temporarily, then install that program and reinstall Bitdefender afterwards....
So, after trying the uninstall process one more time and using CCleaner, restart your device and check again if the VPN still reinstalls automatically....
I've uninstalled it three times now and reinstalled it three times. In Bitdefender Central it says its registered and protected This is the correct name for it....