Min Elements to Remove to Make Almost Sorted Array

An array of integers is almost sorted if at most one element can be deleted from it to make it perfectly sorted, ascending. For example, arrays [2, 1, 7], [13, 9, 2], and [1, 5, 6] are almost sorted because they have 0 or 1 elements out of place. The arrays [4, 2, 1] and [1, 2, 6, 4, 3] are not because they have more than one element out of place.

Given an array of n unique integers, determine the minimum number of elements to remove so that it becomes almost sorted.