Question: - The green is partly covered by snow can I either move my ball or remove the snow.
Answer: - You can do either.
Snow and Natural Ice, other than frost, are either casual water or loose impediments, at the option of the player. (Definitions R&A Rules casual water)
So you can either move the ball so that there is no snow or ice on the line of the putt or you can clear away the snow or ice.
Dew and frost are not casual water or loose impediments so you can not get relief. (Definitions R&A Rules casual water and loose impediments)
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