DeleteCases

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

Examples

Remove specific elements:

DeleteCases[{1, a, 2, b, 3}, _Symbol]
(* {1, 2, 3} *)

Remove by value:

DeleteCases[{1, 2, 3, 2, 1}, 2]
(* {1, 3, 1} *)

Please visit the official Wolfram Language Reference for more details.