How do you stop these unwanted text messages from this number and others like it.  They talk about gov't debt and how they can help you if you owe$15,000 or more.
I don't owe the gov't and I don't want to be charged for their text messages.

I just rec'd a text from this phone number and I do not owe any money to the IRS! I did text them back stating they need to remove me from there phone list as I am on the do not call list. I'm not sure if it will help.

Your best bet is to NOT reply at all.  Simply delete the message and move on.  Whomever this is wants you to reply.  They are fishing for numbers.

Through most of the major carriers, you can block text messages.  This will help you to avoid charges from receiving text messages.  Some of the carriers allow you to selectively block numbers.

Do you owe $10,000+ to the IRS? Our gov't approved program can REDUCE BACK TAXES by over 70%. Reply "yes" to see if you qualify! (optout, reply:out)

They wanted to offer debt relief.

I do not know who this is.