Switched from iPhone to Android, still getting iMessages on iPhone?

Just recently switched from an iPhone 4S to a HTC One Google Edition. For whatever reason, my number is still linked to my phone, so when other iPhone users try to text me, it picks up as me owning an iPhone and sends it to my old iPhone. I would like to keep iMessage on my old iPhone but through my email only, not through my phone number if possible.

Added (1). I wish it was my through email, but its not. I tested myself, if I use an iPhone to send a message to my number, it defaults to iMessage.

Added (2). Yeah you're not allowed to deselect your phone number on an iPhone. You can on an iPod and iPad but not iPhone

It most likely is through the email.iMessages can be sent to a number or an email or both. This is likely what is happening now.

Check the Settings (Messages)

To change the settings so that they will only be sent using your email and not your phone number:
1) Go to Settings
2) Scroll down to Messages
3) Scroll down past the iMessage option until you see Send & Receive click on that option
4) uncheck the button that says your phone number and select the one that is your email