My child is receiving unwanted text messages from some former friends. How do I disable the text messaging feature?

I found a 2-year old thread here on cellphoneforums that said "call *61 and tell the service provider [Verizon in our case] to shut text messaging off." Is that still the best way, 2 years later?

you can use www.vtext.com to block certain numbers/email addresses from texting. If your problem can be narrowed down to 10 senders, and you want the feature to remain active, then start there

If you are trying to block all text messaging entirely, you can still call customer service (*611) and have the feature completely blocked. Another option is to change your child's mobile number, though it is a little more extreme. This option will effectively keep those former firends from being able to text message your child, but still allow for other text messaging to occur.

tell your kid to break their former friends phones?

or like has been said up to 10 numbers can be blocked, or completely disabled.