Implement option to remove profile owner on primary user

[ghost]

When test dpc is set as profile owner on primary user it cant be removed because the option to remove device owner is grayed out Please implement it

[jscott1989]

I believe this is actually a limitation of Android - Profile Owners on the primary user are not able to remove themselves.

Assuming testOnly is set as true on your build - you can remove it using adb.

We won't be able to make changes to this in Android U but it might tie into some things we're doing in the next version after that.