Answer:
You need to contact the easement department of the utility company that owns the easement and ask for a release. The utility must research the easement in their records which is sometimes a very complicated process. They may require a fee for the research and release. That fee can run in the hundreds of dollars. On the other hand they may refuse to release it at all even if it is not in use. Once they have property rights some utility companies don't let them go.