I see one of our valued community members has provided information to assist you. The factory reset process will help remove your phone number from your Droid Maxx.
This process would result in your device being reset to its factory settings.
However, before you consider doing a factory reset on your device, it's very important to make sure you're using cloud services to back up your stored data (e.g., contacts, pictures, videos, music, call history, documents, etc.) or you'll lose the data on your device. We certainly don't want that to happen.
Here are the steps to assist you with this process at http://spr.ly/6606z25Ks.