diff --git a/homeassistant/components/coolmaster/__init__.py b/homeassistant/components/coolmaster/__init__.py
index 5892ef091d9..18a3e943bbc 100644
--- a/homeassistant/components/coolmaster/__init__.py
+++ b/homeassistant/components/coolmaster/__init__.py
@@ -5,8 +5,9 @@ from pycoolmasternet_async import CoolMasterNet
 from homeassistant.const import CONF_HOST, CONF_PORT, Platform
 from homeassistant.core import HomeAssistant
 from homeassistant.exceptions import ConfigEntryNotReady
+from homeassistant.helpers import device_registry as dr
 
-from .const import CONF_SWING_SUPPORT
+from .const import CONF_SWING_SUPPORT, DOMAIN
 from .coordinator import CoolmasterConfigEntry, CoolmasterDataUpdateCoordinator
 
 PLATFORMS = [Platform.BINARY_SENSOR, Platform.BUTTON, Platform.CLIMATE, Platform.SENSOR]
@@ -48,3 +49,14 @@ async def async_setup_entry(hass: HomeAssistant, entry: CoolmasterConfigEntry) -
 async def async_unload_entry(hass: HomeAssistant, entry: CoolmasterConfigEntry) -> bool:
     """Unload a Coolmaster config entry."""
     return await hass.config_entries.async_unload_platforms(entry, PLATFORMS)
+
+
+async def async_remove_config_entry_device(
+    hass: HomeAssistant,
+    config_entry: CoolmasterConfigEntry,
+    device_entry: dr.DeviceEntry,
+) -> bool:
+    """Remove a config entry from a device."""
+    return not device_entry.identifiers.intersection(
+        (DOMAIN, unit_id) for unit_id in config_entry.runtime_data.data
+    )
diff --git a/tests/components/coolmaster/test_init.py b/tests/components/coolmaster/test_init.py
index f8ff761517f..cd3693c513c 100644
--- a/tests/components/coolmaster/test_init.py
+++ b/tests/components/coolmaster/test_init.py
@@ -1,7 +1,12 @@
 """The test for the Coolmaster integration."""
 
+from homeassistant.components.coolmaster.const import DOMAIN
 from homeassistant.config_entries import ConfigEntry, ConfigEntryState
 from homeassistant.core import HomeAssistant
+from homeassistant.helpers import device_registry as dr
+from homeassistant.setup import async_setup_component
+
+from tests.typing import WebSocketGenerator
 
 
 async def test_load_entry(
@@ -22,3 +27,45 @@ async def test_unload_entry(
     await hass.config_entries.async_unload(load_int.entry_id)
     await hass.async_block_till_done()
     assert load_int.state is ConfigEntryState.NOT_LOADED
+
+
+async def test_registry_cleanup(
+    hass: HomeAssistant,
+    load_int: ConfigEntry,
+    hass_ws_client: WebSocketGenerator,
+) -> None:
+    """Test being able to remove a disconnected device."""
+    entry_id = load_int.entry_id
+    device_registry = dr.async_get(hass)
+    live_id = "L1.100"
+    dead_id = "L2.200"
+
+    assert len(dr.async_entries_for_config_entry(device_registry, entry_id)) == 2
+    device_registry.async_get_or_create(
+        config_entry_id=entry_id,
+        identifiers={(DOMAIN, dead_id)},
+        manufacturer="CoolAutomation",
+        model="CoolMasterNet",
+        name=dead_id,
+        sw_version="1.0",
+    )
+
+    assert len(dr.async_entries_for_config_entry(device_registry, entry_id)) == 3
+
+    assert await async_setup_component(hass, "config", {})
+    client = await hass_ws_client(hass)
+    # Try to remove "L1.100" - fails since it is live
+    device = device_registry.async_get_device(identifiers={(DOMAIN, live_id)})
+    assert device is not None
+    response = await client.remove_device(device.id, entry_id)
+    assert not response["success"]
+    assert len(dr.async_entries_for_config_entry(device_registry, entry_id)) == 3
+    assert device_registry.async_get_device(identifiers={(DOMAIN, live_id)}) is not None
+
+    # Try to remove "L2.200" - succeeds since it is dead
+    device = device_registry.async_get_device(identifiers={(DOMAIN, dead_id)})
+    assert device is not None
+    response = await client.remove_device(device.id, entry_id)
+    assert response["success"]
+    assert len(dr.async_entries_for_config_entry(device_registry, entry_id)) == 2
+    assert device_registry.async_get_device(identifiers={(DOMAIN, dead_id)}) is None