Minecraft Bedrock PS4: HOW TO UNLINK YOUR Microsoft ACCOUNT
If you have registered a Mojang account and would like to deactivate your account, please visit your account settings page. Old Minecraft accounts (where you log into Minecraft with a username) do not have a deactivation feature. To deactivate an old Minecraft account, you must first migrate it to a Mojang account. If you want to fully delete your account, please contact Minecraft support and provide your transaction ID.