Based on your code I'll assume the following:
1- acct1 is an array of Objects (type is inconsequential, probably
String)
2- deleteItem() finds the matching item in the array and sets the Object at that index to null.
Suggestions for improvment:
1- use equals() instead of compareTo().
2- use an ArrayList instead of an array.
3- use remove() on the ArrayList to remove the item.