DeleteCases

DeleteCases[expr,pattern] removes all elements of expr that match pattern. 

DeleteCases[expr,pattern,levelspec] removes all parts of expr on levels specified by levelspec that match pattern. 

DeleteCases[expr,pattern,levelspec,n] removes the first n parts of expr that match pattern. 

DeleteCases[pattern] represents an operator form of DeleteCases that can be applied to an expression.

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