Create challenge_9.md

Signed-off-by: Rishav986 <starsiwach132003@gmail.com>

Author: shivaylamba

Challenges/challenge_9.md

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+## Welcome to Challenge 9
+
+Welcome to the ninth challenge! 
+
+Today's task is a continuation of yesterday's task [Task 8](https://github.com/scaleracademy/scaler-september-open-source-challenge/blob/main/Challenges/challenge_8.md?plain=1).
+
+Yesterday the task was to create an additional commit in your branch. And today's focus will be to remove that commit that has been pushed from the pull request created in previous challenges. The main purpose of this is because there can be times when you might push an unncessary or wrong commit and you way want to remove it from your pull request. 
+
+This can be done by using the following command: ``git reset``
+
+Here is an article you can refer to for understanding how git reset works: https://www.atlassian.com/git/tutorials/undoing-changes/git-reset#:~:text=a%20shared%20repository.-,Summary,Index%2C%20and%20the%20Working%20Directory.
+
+So the task is to identity the commit id of the commit you want to remove, use the git reset command, and remove the commit from the pull request by force pushing into it. 
+
+
+Task: 
+1. Identify the commit id that needs to be removed (you should have created this in the 8th Challenge)
+2. Use git reset and force push, to remove the commit from your pull request. 
+3. Share a screenshot of this, in the issue you created in previous challenges.