JetBrains and Hyperskill profiles are two separate profiles.
You can use your JetBrains profile to register and log in to the Hyperskill. In this case, if you delete your JetBrains profile, you won’t be able to log in to the Hyperskill. Resetting your password (using the email address you used for the JetBrains profile) will help you restore access to the Hyperskill.
In other words, your Hyperskill profile will remain intact even after deleting the JetBrains profile you used to log in.