Align the suction pipe of the vacuum cleaner with the keyhole of the door lock to suck the dust out.
Then wipe with a lemon in a dirty place.
Finally, wrap the door handle with a clean rag and turn it by hand to see that the handle is just like the new one.
When cleaning the door handle, you need to pay attention: the lemon will be cut and placed for 1 minute before use, the effect will be better; after cleaning, you can drop a little oil in the key space to prevent it from rusting and make the door easier to open. If the metal handle has black rust formed by oxidation, it can be removed with a toothbrush.
The above cleaning method can be used for both metal and plastic handles.