This is a very stubborn situation... We have one last thing to try before a reboot is necessary. We are going to temporarily trick the `swapoff` command by creating a "dummy" device file... Please run the following commands as **root**:

1.  **Find the Major/Minor numbers:**
    ```bash
    ls -l /dev/sda1
    ```

2.  **Create a temporary, dummy block device file:**
    ```bash
    mknod /dev/sda1 b 8 1
    ```

3.  **Now, try to turn off the swap again.**
    ```bash
    swapoff /dev/sda1
    ```

4.  **Verify the swap is gone:**
    ```bash
    cat /proc/swaps
    ```

5.  **Clean up the dummy device file:**
    ```bash
    rm /dev/sda1
    ```