WhatsApp is a cross-platform mobile messaging app. It is enriched with several features, some of which allow its users to strike out content from their message. Find out with some very simple tips how to do it too.
Steps
Part 1 of 2: With device running iOS

Step 1. Open the WhatsApp application
The app icon looks like a green bubble around a white phone handset.

Step 2. Tap Discussions
You will see this icon at the bottom left of your screen. It looks like two conversation bubbles.

Step 3. Tap on the conversation
Tap the conversation where you would like the strikethrough to appear.

Step 4. Tap the text box
This field is located at the bottom of the screen. By doing so, the keyboard will appear.

Step 5. Write your message to the level where you want to strike it out

Step 6. Add ~
Put a first tilde to mark the start of your strikethrough text.
- You can find the ~ symbol by typing 123 or the button.? 123, then tapping the button #+=. Press the ~. This is the fourth button on the left in the second row.

Step 7. Write the message you want to strike out
Do not enter a space between the ~ and the first letter of your text.

Step 8. Add a second ~ at the end of the text to strike out
This ends the crossed out tag.
Do not enter a space between the last letter of the text and the symbol. By doing so, the text framed by the ~ will be crossed out

Step 9. Continue to write the rest of your post

Step 10. Press ► to send your message
The message will be sent with the text that will appear with a line crossing it without the ~ at both ends.
Part 2 of 2: With device running on Android

Step 1. Open the WhatsApp application
The app icon looks like a green bubble around a white phone handset.

Step 2. Press DISC
You will see this icon at the top left of your screen.

Step 3. Tap on the conversation
Tap the conversation where you would like the strikethrough to appear.

Step 4. Tap the text box
This field is located at the bottom of the screen.

Step 5. Write your message to the level where you want to strike it out

Step 6. Add ~
Put a first tilde to mark the start of your strikethrough text.
You can find the ~ symbol by typing Sym or 12 # located at the bottom left of the screen, then by typing 1/2. Press the ~. This is the second button on the left (or the third depending on some models) in the second row

Step 7. Write the text you want to strike out
Do not enter a space between the ~ and the first letter of your text.

Step 8. Add a second ~ at the end of the text to strike out
This ends the crossed out tag.
Do not enter a space between the last letter of the text and the symbol. By doing so, the text framed by the ~ will be crossed out

Step 9. Continue to write the rest of your post

Step 10. Press ► to send your message
The message will be sent with the text that will appear with a line crossing it without the ~ at both ends.