Delete[expr, n] deletes the element at position n in expr. If n is negative, the position is counted from the end. Delete[expr, {i, j, ...}] deletes the part at position {i, ...

Functions for manipulating elements in explicit lists. This gives a list with x prepended. This inserts x so that it becomes element number 2.

Mathematica provides a carefully chosen set of functions for accessing elements of lists either using indices or positions, or using patterns or criteria for their values.

WindowElements is a notebook option that specifies the elements to include in the window used to display the notebook on the screen.

NotebookDelete[notebook] deletes the current selection in the notebook corresponding to the specified notebook object. NotebookDelete[] deletes the current selection in the ...

AppearanceElements is an option for functions like Manipulate that specifies what elements should be included in the displayed form of the object generated.

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 ...

Union[list_1, list_2, ...] gives a sorted list of all the distinct elements that appear in any of the list_i. Union[list] gives a sorted version of a list, in which all ...

DeleteContents is an option for DeleteDirectory that specifies whether the contents of directories should automatically be deleted.

DeleteFile["file"] deletes a file. DeleteFile[{"file_1", "file_2", ...}] deletes a list of files.