How to hide previously used items in dropdown list?

In Excel, you can quickly create a normal dropdown list, but have you ever tried to make a dropdown list when you choose one item, the previously used one will be removed from the list? For example, if I have a dropdown list with 100 names, as I select a name, I want to delete this name from the drop down list, and now the dropdown contains 99 names, and so on until the drop down list is empty. Maybe, this is some difficult for most of us, and here, I can talk about how to create such a drop down list in Excel.

Hide previously used items in drop down list with helper columns

Hide previously used items in drop down list with helper columns

Supposing you have a list of names in Column A as following screenshot shown, then follow the below steps one by one to finish this task.

1. Besides your name list, please enter this formula =IF(COUNTIF($F$1:$F$11,A1)>=1,"",ROW()) into cell B1, see screenshot:

Note: In the above formula, F1:F11is the cell range that you want to put the drop down list, and A1 is your name cell.

2. Then drag the fill handle over to the range that contain this formula, and you will get the following result:

3. And go on applying a formula in Column C, please type this formula: =IF(ROW(A1)-ROW(A$1)+1>COUNT(B$1:B$11),"",INDEX(A:A,SMALL(B$1:B$11,1+ROW(A1)-ROW(A$1)))) into cell C1, see screenshot:

4. Then fill this formula down to the range you need, see screenshot:

5. Now you need to define a range name for these names in Column C, select C1:C11 (the range you apply formula in step 4), and then click Formulas > Define Name, see screenshot:

6. In the New Name dialog box, type a name in the Name text box, and then enter this formula =OFFSET(Sheet2!$C$1,0,0,COUNTA(Sheet2!$C$1:$C$11)-COUNTBLANK(Sheet2!$C$1:$C$11),1) into the Refers to field, see screenshot:

Note: In the above formula, C1:C11 is the helper column range that you have created in Step 3, and the Sheet 2 is the current sheet you are using.

7. After finishing the settings, then you can create a drop down list, select cell F1: F11 where you want to put the drop down list, then click Data > Data Validation > Data Validation, see screenshot:

8. In the Data Validation dialog box, click Settings tab, then choose List from the Allow drop down list, and then under Source section, enter this formula: =namecheck, (namecheck is the range name you are created in Step 6), see screenshot:

9. And then click OK button to close this dialog, now, the drop down list have been created in the selected range, and after selecting one name from the drop down, this used name will be removed from the list and it only shows the names that have not been used, see screenshot:

Tip: You cannot remove the helper columns you make in above steps, if you remove them, the drop down list will be invalid.

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