You may refer to either these videos or the steps below:

Step 1. Remove the cleaning tray.

Cleaning tray removed.

Step 2. Clean it with a brush using tap water.

Wash cleaning tray.

Step 3. Wipe the base with a clean, damp cloth.

Detachable base of the dock.

Step 4. Reinstall the cleaning tray.

Cleaning tray re-installed.