Can I edit the field "Did this user confirm manually" as an admin

I know that I might be misusing the system. One year ago our Database had more than 6000 addresses. Now since implementing GDPR weare down to 1100 addresses where after a couple of reminders, the peoople have manucally confirmed their request for the Newsletter.
I would like to send Newsletters only to people who have manually confirmed. That makes sense. But some people give me their confirmation on a paper list at the end of an event, others, like members give the confirmation in the membership form. Some of them are too lazy or too old to click on the confirm button. Is there any way that I can, as an adminstrator change the value for these type of people to “1” for “did this user confirm manually?”.
But even though I am asking, I know that I am actually not using the system as it is meant. as this field is exactly the documentation of when an user OKd the Newsletter ;-(