Hi, and thank you for asking your question.
First off, please open up www.gmail.com; after you are automatically signed in to the other (new) account, click on the blue icon/email address at the top-right corner of the page, and Sign out.
You will then be signed out of that account, and brought back to the login page. There, click Sign in with another account at the bottom, and then sign in to your own account accordingly. This should do it.
If you need any further assistance with this issue, please be sure to reply back to me below.
Otherwise, if you could kindly click on (and submit) one of the stars at the top of this page to rate my service, I'd greatly appreciate it. Thank you.