The commission may authorize any public utility to discontinue, temporarily or during such portion of each year as the commission may deem expedient, any part of its service whenever it shall appear that such temporary or seasonal discontinuance will not unreasonably inconvenience the public, or to discontinue the same permanently and remove the equipment essential to the same, whenever it shall appear that the public good does not require the further continuance of such service. The commission, upon its own motion or upon petition of any interested party, may make an order withdrawing from a public utility its authority to engage in business in all or any part of the territory in which it is authorized to operate whenever it shall find, after notice and public hearing, that said utility has declined or unreasonably failed to render service in said territory or that its service in said territory is inadequate, no sufficient reason for such inadequacy appearing.