I know this thread is old, but perhaps it will help present searches.
I disabled my T-Mobile account on a Galaxy s5 SM-G900t, running KitKat 4.4.2 without rooting.
I disabled T-Mobile My Account, T-Mobile Name ID, T-Mobile TV, T-Mobile Software Update, Google Play Music, and ChatON with "Package Disabler" (I think it was free from Google Store)
The reason I disabled is because my cell is unlocked and running on AT&T. I don't want nor need T-Mobile, but it was constantly updating TM stuff. Hope this is of help.