I have written about default lakehouse of a Fabric notebook before here and here. However, unless you used the notebook API, there was no easy/quick way of removing all/selective lakehouses or updating the default lakehouse of a notebook. But thanks to tip from Yi Lin from Notebooks product team,
notebookutils.notebook.updateDefinition
has two extra parameters,defaultLakehouse
anddefaultLakehouseWorkspace
which can be used to update the default lakehouse of a notebook. You can also use it to update environment attached to a notebook. Below are some scenarios how it can be used.
Click through for those scenarios.