updated the merge and rebase section

Author: alexDiaconuAlex

README.md

@@ -311,6 +311,37 @@ Because both branches had moved forward independently, Git created a `merge comm
 * the history shows exactly that parallel work happened
 * nothing was rewritten
 
+### Now you want to erase all the commits that you have created so far from both branches.
+
+Go to `<your-merge-branch-name>` and delete the commits that you created using:
+
+   ```console
+   git switch <your-merge-branch-name>
+   git reset --hard HEAD~n
+   ```
+Replace n with the number of commits you created on this branch.
+
+After that, visualize the log:
+
+   ``` console
+   git log --oneline --graph --all
+   ```
+
+Do the same on the main branch.
+
+   ``` console
+   git switch main
+   git reset --hard HEAD~n
+   ```
+
+Again, replace n with the number of commits you created on the main branch.
+
+Verify the result:
+
+   ``` console
+   git log --oneline --graph --all
+   ```
+
 ## What is `git rebase`?
 
 `git rebase` takes the commits from one branch and `replays them on top of another branch`,
@@ -444,7 +475,8 @@ So instead of:
 you now get:
 
    ``` console
-   A---B---C---D'---E'
+      main:         A---B---C
+      your-branch:          D'---E'
    ```
 
 > [!IMPORTANT] D' and E' are new commits created by `rebase`.
@@ -455,6 +487,46 @@ They may contain the same changes, but they are rewritten commits.
 * the result looks like the work happened in a straight line
 * there is usually no merge commit
 
+
+### Now you want to remove all the commits created during this rebase exercise.
+
+After the rebase, the commits created during this exercise are still on `<your-rebase-branch-name>`, but they were rewritten on top of `main`.
+
+First, go to `<your-rebase-branch-name>` and delete the rebased commits that you created:
+
+   ```console
+   git switch <your-rebase-branch-name>
+   git reset --hard HEAD~n
+   ```
+Replace n with the number of commits you created on this branch.
+
+After that, visualize the log:
+
+   ``` console
+   git log --oneline --graph --all
+   ```
+
+Now switch to the `main` branch and delete the commit that you created there:
+
+   ``` console
+   git switch main
+   git reset --hard HEAD~n
+   ```
+
+Replace n with the number of commits you created on the main branch during this exercise.
+
+Visualize the history again:
+
+   ``` console
+   git log --oneline --graph --all
+   ```
+
+If needed, delete `<your-rebase-branch-name>` as well:
+
+   ``` console
+   git branch -D <your-rebase-branch-name>
+   ```
+
 ## Configure Merge Strategy
 
 We want to configure Rebase and merge as the only merge strategy.