You are able to proceed to an account deletion Soundiiz and removed all saved data on Soundiiz servers at any time directly in your user settings as long you don't have an active Premium subscription.
To access to your User Settings, select the Setting icone near your Username/Avatar in top left of the interface.
If you have an error here, you probably didn't filled the right password or you still have an active Premium subscription (in that case, the subscription will be set to canceled anyway).
Wrong password: If you have created a Soundiiz account with Facebook/Twitter/Google/Apple (be sure to use the right generated Apple email), you will have to use a Soundiiz password to confirm the delete process. You can generate a Soundiiz password on this page.
Premium users: if you have an active Premium subscription, you must first set to cancel your subscription and wait until the end of the current Premium period. Once over, you will be able to delete your account directly in your user settings.
Be aware that deletion will remove definitively your Soundiiz account and data but you will have to revoke each access you have granted to music services to Soundiiz directly in the music service interface.