To delete your user account, you first need to sign in (click "Forgot password?" and follow the instructions. If you don't remember your password, follow this guide: reset password).
Click on your name at the top right and select "My profile".
Click on the "GDPR"-tab in the left menu.
In this view, you'll find all the details Boardeaser can find about you. Boardeaser constantly tries to index and find information that can be associated with you.
Click on "Cancel my account" at the bottom of the page.