Calendar Input Settings is located under My Calendar > Settings > Input.
Calendar Input Fields
Event editing fields to show
Restrict your event authors from using certain fields, or reduce the number of fields you see when creating or editing events, use these options to remove the fields you do not plan to use.
An example. Uncheck Categories and Event Location. Click Save Input Settings. Go to create a new (add) Event or open an existing event. Notice Categories and Event Location have been removed. This will remove Categories and Event Locations for all users.
An alternative method is to use Screen Options in the Add Event or existing event screen to hide e.g. Categories and Event Location for all events.
This will remove Categories and Event Locations just for my user.
Notice the two different approaches. Output Settings will removes a field for all users. Screen Options removes it just for ones own user.
Save custom values to change location text fields into dropdowns. One field per line. Format:
Name of Location.