I am trying to locate where the option for these 3 fields are and how I can remove them or hide them since the fields are unused.
I believe only service contract can be "removed" by hiding it via Setup > Assets > Options. The field isn't always hidden though as it will appear when a new asset is added and it will always appear for admins since they have edit capability as a minimum no matter what the setting is. If you hover over Technician Asset Permissions it will explain how the field will act in the environment per setting.
I am not aware of a standard way to hide/remove the reservable or lease exp fields.
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