Your question is confused: you ask that you want to "sort a cell array based on the number of rows in each cell", but then later you state that you "want to remove all cells with 1 or 2 rows."
So which do you want to do: sort or delete the cell array?
Here is how you can delete those cells:
NrowsB = cellfun('size',mycellarray,1) ;
mycellarray(NrowsB<3) = []
Here is how you can sort those cells:
[~,idx] = sort(NrowsB);
mycellarray = mycellarray(idx);
