How to prevent double voting in a voting form based on special voters code and then removing that value or changing it after each vote

Hi there. 

I am creating an election voting form for an association officers election. Everything is working just fine. As a security measure, I have turned on "prevent multiple submission" option on the form which in principles uses ip address of the client devices to determine who has voted previously. 

However, I have an additional requirement to:

Remove their voter's code from the list so that if someone tries to use that same id to vote from another location or computer they will not be able to vote because their code is no more available on the valid list of codes. 

For example, If we have 5 valid voters codes that the system is checking against to validate the users after a Voter 1 completes their vote, the new list should now show

1 Voter 1 FJKKRNHV

2 Voter 2 JBHMAYQO

3 Voter 3 DXSXTTYR

4 Voter 4 ZCJOHZOX

5 Voter 5 UDMEXBGQ

NEW list should look something like this one

1 Voter 1 FJKKRNHV

2 Voter 2 JBHMAYQO

3 Voter 3 DXSXTTYR

4 Voter 4 ZCJOHZOX

5 Voter 5 UDMEXBGQ

So I am trying to figure out how to deduct this list each time a person cast their vote.

Currently, I am using 

Spreadsheet to form 

Widget to validate the voters. 

You can use the Unique Question feature:

How to set Form Limits Based on a Unique Question

Or you can use the Appointment slot widget. 

Hi Bjoanna,

Thanks for this tip. This is exactly what I missed. Implemented it and all is well. Thanks.