The approach described by @DRMasterChief will not work on newer versions of thirty bees, intentionally.
You can check if your tb_employee table contains column signature - if the column exists, you can't change the email/password in the table manually. You also need to change the value of column signature, but for that you need to know a secret that's not available to mysl.
This mechanism exists to prevent attackers to elevate sql injections into complete access. If your store contained SQL-injection vulnerability (often caused by older third party modules), attacker could use it to change admin password, and then log in (basically the same mechanism described above). With the requirement to change signature as well, this no longer works.
You can use force-login php script to log into your admin, see this post:
You will have to:
upload force-login.php file into your admin123xyz directory (every installation have different admin folder name)
open url https://your.store/admin123xyz/force-login.php
this will logs you in as an admin
change password
delete force-login.php script