Sorry to hear your experiencing account issues.
Here’s some info on the hacking attempts (and successes unfortunately) being carried out by a group of Russian hackers, and what Epic is doing to combat it. There were large “dumps” of usernames (or email addresses) and passwords posted to some hacking forums a while back (not Epic accounts, it was mostly email accounts) which allowed them to brute force other accounts using the same password. If you use the same password for other sites, such as unrealengine.com, the hackers are able to get in.
To ensure no harm can be done please change your password on your email account and on any other sites that use the same password. Use the link in the security bulletin above for the “have I been pwnd” to see if your email address was compromised (mine was, two of my email accounts were compromised).
The hackers are targeting Epic account holders with payment options to purchase Fortnite V-Bucks, which they are then reselling on some pretty shady websites. If you have any purchases listed in your order history that were not made by you (highlight your name top right, select Personal, then Order History) please contact PayPal or your credit card company to inform them of the fraudulent purchases, they have been refunding them for other users.
You can delete your account by contacting Epic Support, to do so please fill out this form. It says Fortnite, but it’s for UE4 support too, just select “PC/Mac” from the Fortnite Game Platform combo-box, select a random Game Mode, and then use “Accounts” option for Game Issue.
Make sure to include all relevant information and they will reply back to you by email asap, but please be aware the support staff are very busy so it may take a couple days for them to get back to you.