You won't find any automated way to delete a Roblox account on its website. Use one of the 3 methods listed in the post to delete Roblox.

How to delete a Roblox account Users or parents who want to delete an account will be unable to find a simple delete button on the Roblox website, however. This is because there isn't one.

To reset Roblox without losing your settings, you need to Clear Roblox Registry entries, Reset Roblox App Data & Clear Roblox Cache.