Short version: Texas state law establishes the right for cities to decide whether their police can engage in collective bargaining.

https://statutes.capitol.texas.gov/Docs/LG/htm/LG.174.htm

The same way you change any other service provider. You find another vendor or renegotiate. The people will vote to instruct their officials to do so. Pretty straightforward.

It happens all too often: https://en.m.wikipedia.org/wiki/Dissolution_of_the_Soviet_Un...