Doing so will open your LinkedIn Home page if you're logged in. If you're not automatically logged in, enter your user name and password and click on Sign In. It's on the right side of the group of options at the top of your screen. You should see your profile picture here. If you don't have a profile picture on LinkedIn, the Me tab will display a person-shaped silhouette. This option is in the drop-down menu below the Me tab. It's on the left side of the row of options near the top of the page. The other options in this row are Privacy and Communications. You'll see this option on the left side of the page below the Basics and Third parties tabs. It's near the bottom of the page. This link is below the "Account Type" heading on the right side of the page. If you bought your Premium subscription through Apple, you'll see a message that says "Your subscription was purchased via the iTunes store. Please contact Apple to make any changes to your subscription" here. You'll need to cancel your subscription from within the iTunes store instead. Your options include the following:  I upgraded for a one-time use/project only I didn't use the Premium account features Price is too high The features didn't work as expected Other It's in the bottom right corner of the screen. Depending on the reason for cancelling you chose, you may need to type in an explanation before you can click Continue. It's the blue button in the bottom right corner of your screen. Doing so will cancel your Premium subscription and prevent you from being billed when your current billing cycle comes to an end. After doing so, you'll be able to delete your LinkedIn account if you so choose.

TL;DR in Vietnamese:
Mở trang web LinkedIn. Nhấp vào thẻ Me (Tôi). Nhấp vào Settings & Privacy (Cài đặt & riêng tư). Nhấp vào thẻ Account (Tài khoản). Nhấp vào Subscriptions (Đăng ký). Nhấp vào Manage Premium Account (Quản lý tài khoản cấp cao). Nhấp vào Cancel subscription (Hủy đăng ký). Chọn lý do hủy. Nhấp vào Continue (Tiếp tục) ở góc dưới bên phải màn hình. Nhấp vào Cancel my subscription (Hủy đăng ký). Nhấp vào Go to my homepage (Trở về trang chủ).