Please give us a way to turn off iMessage on all computers and devices

iMessage is DANGEROUS to use because it loses messages from and to non-Apple users.

There are instructions from non-Apple to turn off iMessage on all our devices, but they DO NOT WORK! I have through the instructions turning off iMessage on every one of my computers and devices, even charging up old retired iPhones enough to turn it off on them. Unfortunately several of my phones and computers have been junked so I can’t turn off iMessage on them. I presume that perhaps iMessage was turned on on one or more of them, and that this is the reason iMessage insists on remaining on, or refuses to offer MSM, on all of my current computers and devices.

Right now on this iPad, even though I had iMessage turned off, when I tap the Messages blob, I can do nothing because all it offers is the window to give my iCloud username and password to turn iMessage back on.

PLEASE give us instructions to turn off iMessage on all our computers and devices so we can use the vastly more popular MSM text.