Have you got someone who helps you with your email marketing? You should invite them to your account so they have their own log in details which you can revoke access to at anytime. You will also be able to control what level of access they have to your account. Heres the 4 types of accounts you can allow them to have.
Can only access reports
Has access to reports plus the ability to create/edit campaigns, templates and automations, but can’t send campaigns.
Has full access except for billing, add-ons, user managements, and list exports.
Account user with full access.
So do this, you simply log into your MailChimp account and go to your Account.
Select Account settings > Account users.
Now simply select Invite A Users to the right of the page.
Here you can select the access you want them to have to your account.
Once done select Invite User at the bottom, then the user you have invited will receive an email which expires after 7 days. They can then select their own username/password.