Given an item in the DOM, use querySelector() to identify it, like this:

const item = document.querySelector('#itemId')

then, to remove all its children elements, you have a few different solutions.

The fastest way looks like this:

item.innerHTML = ''

Another solution that is suggested is this: create a loop, check if the firstChild property is defined (the element has at least a child) and then remove it:

const item = document.querySelector('#itemId')
while (item.firstChild) {
  item.removeChild(item.firstChild)
}

The loop ends when all children are removed.

The first, in most performance benchmarks I checked, looks like being the fastest solution.