ClearAttributes

ClearAttributes[symbol, attr] removes attr from the list of attributes of the symbol.

Examples

Remove Listable attribute:

SetAttributes[f, Listable]
ClearAttributes[f, Listable]
Attributes[f]
(* {} *)

Remove multiple attributes:

ClearAttributes[g, {Flat, Orderless}]

Remove from multiple symbols:

ClearAttributes[{f, g}, Listable]

Please visit the official Wolfram Language Reference for more details.