How to clean feng shui monument

No problem, just wipe it clean. As for the impact on future generations, that's nothing.

Think about it, does anyone in your family offend people?

If you want to seek peace of mind, you must keep more good thoughts and do more good deeds, and do no evil except evil thoughts.

If you are too superstitious, you can buy some paper to burn and pray, and be practical.

The root of solving problems is to solve contradictions with others.