There is a LoadBank() method which loads addressable banks in the RuntimeManager:
#if UNITY_ADDRESSABLES_EXIST
public static void LoadBank(AssetReference assetReference, bool loadSamples = false, System.Action completionCallback = null)
However there is no UnloadBank() method to mirror the call and free memory when the bank is not used anymore. From the Unity manual on Addressables:
The basic rule of thumb to avoid “memory leaks” (assets that remain in memory after they are no longer needed) is to mirror every call to a load function with a call to a release function. You can release an asset with a reference to the asset instance itself or with the result handle returned by the original load operation.