打开WhatsApp。 点按屏幕右上角的⋮，打开一个下拉菜单。 点按下拉菜单底部的设置选项，打开WhatsApp的“设置”页面。 点按页面中间的数据和存储用量。 点按页面顶端的存储使用选项。 选择一个对话。 点按屏幕右下角的释放空间。 勾选这一页的所有方框。 点按屏幕底部的清除消息。 出现提示时，点按清除所有消息 。

Given the above summary, write a detailed text in English for it.
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. It's in the top-right corner of the screen. A drop-down menu will appear.  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. Skip the next step if so. This option is at the bottom of the drop-down menu. Doing so will open your WhatsApp settings. It's in the middle of the page. You'll find this option at the top of the page.  If this option is gone, WhatsApp doesn't have any media that you can delete. If you're encountering storage errors and this option is gone, try deleting and reinstalling WhatsApp. Tap the name of a person or a group to open the relevant chat's media page. It's in the bottom-right corner of the screen. Tap each available box to do so. 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 at the bottom of the screen. Doing so will remove all of the selected media from WhatsApp and from your phone.