Clearing out game object list?

I have a bit of code that uses a game object list to destroy everything with a certain tag:

Columns = GameObject.FindGameObjectsWithTag("Column");
			while (ColumnDestroy < Columns.Length)
			ColumnDestroy += 1;

However, I’m not sure how to “reset” the list, specifically so that the length doesn’t ever get more than 6. I know I can hard-code it to stay a 6, but I’d rather have it as dynamic for bug-squashing.

You can either set each value to null as you loop through, or if it’s an array:

Columns = new GameObject[0];

and if it’s a list: