As said previously, you can request an account deletion through a support ticket, however I think you are just having issues improving your gameplay and are getting frustrated trying. Based on your recent history, I would suggest trying to place more wards. You build warding items but your mid laner is still outdoing you in wards when he doesn't have one. Control wards help a lot too to help deny vision so your jungler can gank more consistently.
You also go for expensive items that only give you offense stats even when you are behind. If your lane is doing poorly or one of your enemies is getting fed you can go for something like a locket or redemption to help your team survive in team fights. They have powerful actives that can completely turn around teamfights. You can go for something like a lich bane or echo when ahead a few kills, but keep in mind that the cheaper items exist.
Sorry if I am reading too much into the situation, but I figured some words of advice could possibly help you.