Then there is no real chance.
You can encrypt the data, so that somebody who queries the database only sees encrypted data.
You can limit the rights to only one admin, but one admin will always be able to see the data.
But this is the same in real polls.
The people at the polling station can of course look into the ballot box.
Therefore, these people are considered trustworthy and there are several from different parties.
So if you are not considered trustworthy, just say, "Then do it yourself using the ballot paper method."
Joffm