Answer: Based on your description I am not certain what you are seeing. If it is a mushroom or similar growth on the soil surface, just scrape it off and remove it. This would be growing on decomposing material in the potting mix (such as wood chips) and will not damage the plant.
If there is a fungal infection affecting the leaves on the plant itself, you will need to trim it back quite hard and try to improve the growing conditions. Provide a location with ample sun, good air circulation, and avoid wetting the foliage when you water.
I hope this helps.
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