Delete the emails stored in a Google Form's responses - google-apps-script

Question

Background:
I am trying to create a google form that will be filled out by people, and then send a second form to be filled by someone else (couple). The form response needs to be anonymous, but the responses will also need to be linked.
My solution so far - using a unique ID for linking (kudos -> How to assign a unique ID to a google form input?) then using the email inputted to send off a message with a pre-made link to the next form with the ID and then delete the email address from the sheet.
The Question
The next sanitation which I am stuck on - is removing the email address form the Google Form response. One way would be to use deleteAllResponses() but that will also delete the basic data analysis pre-done by Google that I intend to use (to save time on creating some of the graphs).
I tried to find a way to access the response object and delete/modify the email field, but was unable to achieve that.
Would appreciate the help.
function myFunction() {
//delete the last email that was added
function deleteEmails(Row){
sheet.getRange('B'+Row + ':B'+Row).clearContent();
}
//delete all responses - would like to change this to only delete/modify the email field.
function deleteResponses() {
var form = FormApp.openById('The form ID');
form.deleteAllResponses();
}
//get the data on the sheet
var sheet = SpreadsheetApp.openById("The sheet ID").getSheetByName('Form Responses 1');
var StartRow = 1;
var LastRow = sheet.getLastRow();
var Range = sheet.getRange(LastRow, 2, 1, 62)
var AllValues = Range.getValues();
//if the person disagrees to fill the form - dont send an email
if (AllValues[0][1] != 'disagree') {
var SendTo = AllValues[0][0];
var body = "Thank you for answering pfa a link for the sedond form";
//send the actual email
MailApp.sendEmail({
to: SendTo,
cc: "",
subject: 'Thank you for answering',
htmlBody: body,
});
}
//delete emails and responses
deleteEmails(LastRow)
deleteResponses()
}