The following fields are provided by Lansweeper but we would like to use select lists or a user lookup (for Contact) to avoid data entry errors, similar to what is available for the custom fields. Alternatively disabling these fields so we can use custom fields would work as well.
Contact Location Building Department Branch Office
I've added this to the wish list, though I can't guarantee that this will be implemented unfortunately. While you can't disable the specified built-in fields, you can give custom fields the exact same names and turn those into select lists under Configuration\Asset Pages. (There is no built-in functionality yet however to automatically generate user select lists.)