Accounts created with Google OAuth (by clicking the "Sign Up with Google" button) are linked directly to your Google account. This means that there is no email address / password for your Descript account, and as such it is not possible to disassociate your Google email address.
If you attempt to change the email address associated to your account, you will see the following error message:
"Could not update user: Cannot change email for account login type (google-oauth2)"
Users who are having trouble signing into their account should click the Sign in with Google button instead of filling in a username and password.
If you would like to change the password associated to your Google Account, you may find instructions on how to do so on Google's help page on the topic.