• JS

const idx = items.indexOf(x)
if (idx !== -1) items.splice(idx, 1)

• Clojure

(let [[n m]
      (split-with (partial not= x) items)]
  (concat n (rest m)))

• C++

erase(items, x);

• C#

items.Remove(x);

• D

items = items.remove(items.countUntil!(a => a == x));

• Dart

items.remove(x);

• Elixir

List.delete(items, x)

• Fortran

integer, dimension(:), allocatable :: items

i = findloc(items, x)
if (i /= 0) items = [items(1:i-1), items(i+1:)]

• Go

func removeFirstByValue[S ~[]T, T comparable](items *S, x T) {
	if i := slices.Index(*items, x); i != -1 {
		*items = slices.Delete(*items, i, i+1)
	}
}

• Go

for i, y := range items {
	if y == x {
		copy(items[i:], items[i+1:])
		items[len(items)-1] = nil
		items = items[:len(items)-1]
		break
	}
}

• Go

for i, y := range items {
	if y == x {
		items = append(items[:i], items[i+1:]...)
		break
	}
}

• Go

func removeFirstByValue[S ~[]T, T comparable](items *S, x T) {
	for i, y := range *items {
		if y == x {
			*items = slices.Delete(*items, i, i+1)
			return
		}
	}
}

• Haskell

delete x items

• Java

items.stream().findFirst().filter(item -> "x".equals(item)).ifPresent(removeIndex -> items.remove(removeIndex));

• Java

T value;
for(int index = 0; index < items.size(); index++) {
	value = items.get(index);
	if(value.equals(x)) {
		items.remove(index);
		break;
	}
}

• Java

<T> void remove(List<T> items, T x) {
    Iterator<T> i = items.listIterator();
    while (i.hasNext())
        if (i.next() == x) {
            i.remove();
            break;
        }
}

• PHP

$list_position = array_search($x, $items);
$specific_item = $items[$position];
unset($specific_item);

• Pascal

i := items.IndexOf(x);
if i <> -1 then
  items.delete(i);

• Perl

extract_first_by { $x eq $_ } @items;

• Python

items.remove(x)

• Python

for i in range(len(items)):
    if items[i] == x:
        del items[i]
        break

• Python

del items[items.index(x)]

• Ruby

i = items.index(x)
items.delete_at(i) unless i.nil?

• Rust

if let Some(i) = items.iter().position(|item| *item == x) {
    items.remove(i);
}