ee.List.splice

// An ee.List object.
var list = ee.List([0, 1, 2, 3, 4]);
print('Original list', list);

// If "other" argument is null, elements at positions specified by "start" and
// "count" are deleted. Here, the 3rd element is removed.
print('Remove 1 element', list.splice({start: 2, count: 1, other: null}));

// If "start" is negative, the position is from the end of the list.
print('Remove 2nd from last element', list.splice(-2, 1));

// Deletes 3 elements starting at position 1.
print('Remove multiple sequential elements', list.splice(1, 3));

// Insert elements from the "other" list without deleting existing elements
// by specifying the insert "start" position and setting "count" to 0.
print('Insert new elements', list.splice(2, 0, ['X', 'Y', 'Z']));

// Replace existing elements with those from the "other" list by specifying the
// "start" position to replace and the "count" of proceeding elements. If
// length of "other" list is greater than "count", the remaining "other"
// elements are inserted, they do not replace existing elements.
print('Replace elements', list.splice(2, 3, ['X', 'Y', 'Z']));

# An ee.List object.
ee_list = ee.List([0, 1, 2, 3, 4])
print('Original list:', ee_list.getInfo())

# If "other" argument is None, elements at positions specified by "start" and
# "count" are deleted. Here, the 3rd element is removed.
print('Remove 1 element:',
      ee_list.splice(start=2, count=1, other=None).getInfo())

# If "start" is negative, the position is from the end of the list.
print('Remove 2nd from last element:', ee_list.splice(-2, 1).getInfo())

# Deletes 3 elements starting at position 1.
print('Remove multiple sequential elements:', ee_list.splice(1, 3).getInfo())

# Insert elements from the "other" list without deleting existing elements
# by specifying the insert "start" position and setting "count" to 0.
print('Insert new elements:', ee_list.splice(2, 0, ['X', 'Y', 'Z']).getInfo())

# Replace existing elements with those from the "other" list by specifying the
# "start" position to replace and the "count" of proceeding elements. If
# length of "other" list is greater than "count", the remaining "other"
# elements are inserted, they do not replace existing elements.
print('Replace elements:', ee_list.splice(2, 3, ['X', 'Y', 'Z']).getInfo())