Mint 19.3 login only as user, not as administrator

I am a real newbie. In learning, I created a practice user "jared" and gave him the password "jared". NOW, when my Microsoft Surface Pro 2 having only Linux Mint 19.3 Mate residing thereon, will not let me login as anyone but "jared" with "jared" as password. It boots up with the computer name and it will not authenticate on anything BUT "jared". Nowhere is there a place to login as administrator or "su".

So, how to get out of this pickle? Would be so grateful for some help. Thanks.