How i revert creating partition table inside a partition

It looks like nothing happened because fdisk failed to overwrite your filesystem. When it tried, it showed the error:

Failed to add partition 1 to system: Invalid argument

This is, however, a good time to ensure that your backups are current and restorable. It's possible that something did go wrong anyway.

Note that fdisk did try to warn you about the problem before you did anything. It warned:

The old ext4 signature will be removed by a write command.
 
Device does not contain a recognized partition table.
Created a new DOS disklabel with disk identifier 0x1d9559e3.

It's a good idea to read through the messages that your tools print, even if you are very familiar with them, as something unexpected may appear one day. If you had noticed this, you may have realized something was wrong before any damage may have been done.