Im working with an Unstructured/undated workfile with 6818 observations (people 18 years and older) from 2010 to 2014:

in the picture we can see the variable "A8ANIOTRIM" that reflects the quarter in which the observation appears (for example the person "29462013" appears in the first and second quarter of 2010 and the same for 2011), each observation appears in two quarters of one year and in two quarters of another year.
Then I modify the structure creating a panel data, when I do so, "A8ANIOTRIM" self-modifies and add the two missing quarters of each year (in which the observation does not appear) with no content:

I can not delete it and it does not help me that they appear... help me please
