are you sure the code is doing what you expect?

Your code will delete row 2, then delete the sixth row and then the 10th.

The problem is that once you delete the second row, the seventh row is now
the sixth row and is the next to be deleted. When deleted, the 10th row is
actually the original twelfth row.

In deletion, unless you keep track, you should start at the end and work
backwards.