In most scenarios, a League may not move. While Pokémon Organized Play is the ultimate authority on deciding what Leagues may move, Professors have been able to move Leagues in the following scenarios:

The location of a Store League has ceased to exist, and a nearby store that does not already host a League is willing to host the community.
A Club League wishes to become a Store League, and a nearby store that does not already host a League is willing to host the community.

If the location you are wishing to move your League to already has a League, the existing League in that location will take precedence.

If you believe your League may fit a scenario where it could be moved, you may submit a support ticket at https://support.pokemon.com/hc/en-us/requests/new?ticket_form_id=360000020293, choosing League as the category and Event as the subcategory.