"If you must speak ill of another, do not speak it, write it in the sand near the water's edge."
I assume to allow the water to take the thought away.
Why not try it and see what happens - you might just be surprised.
If you don't live near a beach then writing it on a piece of paper and then ripping it up or setting fire to it (safely) would work. Alternatively writing it in sand in your garden, or children's sandpit, and then watering it would too. Basically anything that allows the thought to be expressed and then expunged (if that's the right word?).
Such a great idea, and aligns well with sayings that keep us stuck too - such as:
Landscaping Your Life
Inspiring change inside and out