How do I lock my iMessages from my iPad
I know how to turn off iMessages in the settings but anyone could turn it back on with out a passcode. How do I put a passcode on it?
iPad Air Wi-Fi
You cannot. Developers can provide locking for their own apps
if they so desire. Apple did not choose to provide locking for
their apps.
You can set the iPad into Guided Access to allow someone to
use only 1 app on your iPad
Use Guided Access with iPhone, iPad, and iPod touch - Apple Support
However there is no provision to block just iMessage.