How to Removing Old Spark Plugs
Check the existing plugs for wear.
It is normal for the spark plug to appear somewhat dirty even if the plug is working properly, but you will need to change your spark plugs if you see any white, limey build up around the electrodes of the plugs, or if you see any evidence of burning or parts of the electrode missing.
Heavy, sooty build-up also suggests that you need to change your plugs.
If the plugs are bent, black, or broken, you may have a mechanical problem with your engine and should consult a qualified mechanic or your local car dealer repair shop without undue delay.