After removing a tree, the grade on the front of my property changed, exposing the water cut off access pipe (not sure what it's actually called). How should I go about cutting it down. Is it a DIY project? Or do I have to engage the water company?
That valve belongs to the water utility and you should not tamper with it.
To get them to address the issue promptly, tell them you fear that it will be damaged/struck by a landscaper during your work and/or that it presents a safety (tripping) hazard. They may need to replace the whole valve, which might require shutting down the water to your street at a main-line valve at the nearest road intersection.