Article in English: Tap the WhatsApp app icon, which resembles a white speech bubble and phone receiver on a green background. This will open the WhatsApp main page if you're logged in. If you aren't logged in, follow the on-screen prompts to enter your phone number and select a username. This gear-shaped icon is in the bottom-right corner of the screen. Doing so opens the Settings menu.  If WhatsApp opens to a chat, first tap the "Back" button in the top-left corner of the screen. If WhatsApp opens to a page with the word "Settings" at the top, you're already in the Settings menu. It's near the bottom of the screen and next to a green square with a ↑↓ icon on it. On an iPhone SE, iPhone 5S, or prior model of iPhone, you may need to scroll down to see this option. This is the bottom option on this page. Tap a chat from which you want to clear the media. You may have to scroll down to find the chat that you want to clear. It's at the bottom of the screen. Doing so opens a list of the types of media that you've sent in the current conversation. Some boxes will be pre-selected; to delete all media from a conversation, make sure that you check every box that's not greyed out. Some boxes will be greyed out because the conversation doesn't contain their media (e.g., if your conversation doesn't have any videos in it, the "Videos" box will be greyed out). It's a red-text button at the bottom of the screen. This will remove all of the selected media from the conversation. Because WhatsApp does not currently have a feature that allows you to delete all the media in the app at once, you'll need to repeat this process for each chat that contains media. You may have to close and re-open WhatsApp before your phone's storage will reflect the free space from the deleted data.

Summary in Chinese:
打开WhatsApp。 点按设置。 点按数据和存储用量。 往下滚动，点按页面底部的存储使用选项。 选择一个对话。 点按屏幕底部的管理。 勾选页面上的每一个方框。 点按屏幕底部以红字显示的清除按钮。 出现提示时，点按清除。 对其它对话重复上述过程。